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Ten advisories, 13 CVEs: Ubuntu and glibc patch code-execution, SQL-injection and denial-of-service flaws across core packages

What's new: Fixes for glibc's strfmon buffer overflow (CVE-2026-19499) and tdelete out-of-bounds stack access (CVE-2026-19542) are now available on Ubuntu 24.04 LTS via USN-8737-2. Upstream, the glibc project newly documented the nscd DNS-response stack overflow (GLIBC-SA-2026-0016, glibc 2.3.4+) and the strfmon/strfmon_l overflow (GLIBC-SA-2026-0017, glibc 2.38-2.44). USN-8571-2 repairs an Apache HTTP…
Merged summary · glm-5.3-flash · rewritten as coverage arrives

Between September 10 and 16, 2026, Ubuntu published eight Security Notices and the GNU C Library project issued two advisories (GLIBC-SA-2026-0016 and GLIBC-SA-2026-0017), covering 13 CVE references plus two unnumbered flaws - glibc strfmon/tdelete and nscd…

Ten advisories were published between September 10 and 16, 2026: eight Ubuntu Security Notices and two GNU C Library advisories, together covering 13 CVE references plus two flaws published without CVE ids. On September 10, USN-8737-2 delivered glibc fixes to Ubuntu 24.04 LTS for CVE-2026-19499, a buffer overflow in strfmon when handling right-justification padding, and CVE-2026-19542, an out-of-bounds stack array access in tdelete; both may allow denial of service or arbitrary code execution. Upstream, GLIBC-SA-2026-0016 (September 11) disclosed an nscd stack overflow from unbounded alloca use that can crash glibc 2.3.4 and newer when an untrusted DNS server returns oversized responses, degrading DNS resolution; exploitation requires nscd to be enabled and an untrusted DNS server in use, and the advisory was posted by maintainer Siddhesh Poyarekar. GLIBC-SA-2026-0017 (September 14) disclosed a buffer overflow in strfmon/strfmon_l affecting glibc 2.38 through 2.44, where right-justified width padding conversions can write past the end of the caller-supplied output buffer and exploitation requires an application path calling strfmon with attacker-influenced parameters - the same right-justification padding flaw Ubuntu fixed as CVE-2026-19499, though the glibc advisory itself names no CVE id. Also on September 10, USN-8743-1 fixed three PHP flaws: SQL injection via incorrect backslash escaping in the PostgreSQL extension (CVE-2026-17543), an out-of-bounds write in bccomp() that could cause DoS or arbitrary code execution on Ubuntu 26.04 LTS (CVE-2026-17544), and unbounded recursion from circular symlinks in phar archives (CVE-2026-7260). USN-8744-1 fixed two Python flaws spanning Ubuntu 14.04, 16.04, 18.04, 20.04, 22.04 and 24.04 LTS: CVE-2026-3644, http.cookies mishandling of control characters allowing arbitrary content injection, and unbounded recursion in the Expat XML parser reached via pyexpat that can crash Python (no CVE id given); no exploitation in the wild is reported. USN-8571-2 fixed an Apache HTTP Server regression in which the USN-8571-1 fix - addressing CVE-2026-33007, a memory-handling flaw in mod_authn_socache allowing remote DoS, and an HTTP response splitting flaw in multiple modules credited to Pavel Kohout, Arkadi Vainbrand, Haruki Oyama, Merih Mengisteab and Dawit Jeong - omitted a library symbol, preventing Apache from starting when HTTP/2 proxying was enabled. On September 16, USN-8736-2 backported the USN-8736-1 Perl fixes to 24.04…

  • Ten advisories were published September 10-16, 2026: eight Ubuntu Security Notices and two glibc advisories (GLIBC-SA-2026-0016, GLIBC-SA-2026-0017), covering 13 CVE references plus two flaws without CVE ids (Python pyexpat recursion,…
  • USN-8737-2 delivers glibc fixes to Ubuntu 24.04 LTS for CVE-2026-19499 (strfmon buffer overflow via right-justification padding) and CVE-2026-19542 (tdelete out-of-bounds stack access); both may allow DoS or arbitrary code execution.
  • GLIBC-SA-2026-0017 discloses a strfmon/strfmon_l buffer overflow affecting glibc 2.38 through 2.44; it names no CVE id but describes the same right-justification padding flaw Ubuntu tracks as CVE-2026-19499.
  • GLIBC-SA-2026-0016 discloses an nscd stack overflow from unbounded alloca use affecting glibc 2.3.4 and newer, triggered by an untrusted DNS server returning oversized responses; impact is degraded DNS resolution.
  • USN-8743-1 fixes three PHP flaws: CVE-2026-17543 (SQL injection in the PostgreSQL extension), CVE-2026-17544 (out-of-bounds write in bccomp()) and CVE-2026-7260 (unbounded recursion via circular symlinks in phar archives).
  • USN-8744-1 fixes Python CVE-2026-3644 (http.cookies content injection) and an unnumbered pyexpat/Expat recursion DoS, affecting Ubuntu 14.04 through 24.04 LTS; no exploitation in the wild is reported.
  • USN-8571-2 fixes an Apache startup failure with HTTP/2 proxying enabled, a regression from USN-8571-1 caused by a missing library symbol; USN-8571-1 addressed CVE-2026-33007 (mod_authn_socache remote DoS) and a multi-module HTTP response…
  • USN-8736-2 backports Perl fixes to Ubuntu 24.04 LTS: CVE-2026-15534 (out-of-bounds heap reads/writes on large regex inputs) and CVE-2026-19487 (security-restriction bypass via incorrect alternative-branch matching).

Coverage timeline

  1. · 7d ago
    Ubuntu Security Notices· 26
    USN-8737-2: GNU C Library vulnerabilities

    Ubuntu extends glibc fixes to 24.04 LTS, patching buffer overflow in strfmon and out-of-bounds access in tdelete, both potentially leading to code execution.

Vulnerabilities in this storyAll →

CVEVulnerabilityCVSSEPSSFlagsAffectedExposurePublished
CVE-2023-23931
cryptography is a package designed to expose cryptographic primitives and recipes to Python developers.

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In affected versions `Cipher.update_into` would accept Python objects which implement the buffer protocol, but provide only immutable buffers. This would allow immutable objects (such as `bytes`) to be mutated, thus violating fundamental rules of Python and resulting in corrupted output. This now correctly raises an exception. This issue has been present since `update_into` was originally introduced in cryptography 1.8.

NVD description · AI analysis pending
6.51% PoC
  • cryptography.io cryptography
CVE-2026-15534
Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch.

Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch. The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it. A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.

NVD description · AI analysis pending
5.7<1%
CVE-2026-17544
+2 in the same advisory: …17543 …7260
Attacker-provided inputs to bccomp() could lead to an out-of-bounds write with stack and heap corruption in PHP versions from 8.4.* before 8.4.24 and from 8.5.*

Attacker-provided inputs to bccomp() could lead to an out-of-bounds write with stack and heap corruption in PHP versions from 8.4.* before 8.4.24 and from 8.5.* before 8.5.9.

NVD description · AI analysis pending
8.1
group max
<1%
  • php php
CVE-2026-19487
Perl regex engine flaw yields incorrect match results via stale failure flag

Perl versions from 5.9.4 before 5.41.9 can produce incorrect regular-expression match results because a stale failure flag in the Aho-Corasick prescan (S_find_byclass) is not cleared when a later transition succeeds, causing the prescan to stop before it records an earlier valid match position. The flaw is triggered by alternation patterns where one candidate position is recorded and a later character then forces a fallback through a fail link that succeeds; for example, 'ABCDE' =~ m/ABCF|BCDE|C/ matches C at offset 2 instead of BCDE, and m/ABCF|BCDE|C(G/) fails to match at all. An attacker who controls input to such a regex can make an access-control, validation, or filtering decision resolve incorrectly, either matching the wrong alternative branch or missing a match entirely, with impact rated low (CVSS 5.3, medium). Any application running an affected Perl interpreter whose security-relevant regexes use alternations is exposed, and because Perl ships by default with virtually all Linux and Unix systems the installed base is enormous even though only specific pattern shapes trigger the bug. No public proof-of-concept is known, the issue is not in CISA KEV, and EPSS puts the 30-day exploitation probability at 0.4%, so no exploitation is currently known.

Do: Upgrade to Perl 5.41.9 or later, or apply vendor backports such as Ubuntu's USN-8736-1 for affected distribution packages. Audit regex-based access-control, validation, and filtering rules that use alternations, and test them against inputs where a later alternative should match after an earlier one fails. No reliable workaround exists because the defect is inside the regex engine itself, so patching is the primary remediation.

5.3<1%
  • Perl >= 5.9.4 and < 5.41.9 (fixed in 5.41.9)
  • Ubuntu perl (distribution packages)
masshundreds of millions of installations (Perl is bundled by default with nearly all Linux/Unix distributions)
CVE-2026-19499
Buffer overflow in glibc strfmon() width padding affects glibc 2.38–2.44

The strfmon() and strfmon_l() functions in the GNU C Library (glibc) versions 2.38 through 2.44 can write past the end of a caller-supplied buffer when a monetary conversion uses right-justified width padding. The overflow occurs when the destination buffer is large enough for the padding itself but too small for an internal memmove operation, with the field width or format string potentially attacker-influenced or a fixed susceptible pattern in the calling code. Successful exploitation yields out-of-bounds memory writes in the context of the calling application, plausibly causing crashes (denial of service) or, depending on heap layout, code execution. Any Linux application linked against glibc 2.38–2.44 that calls strfmon/strfmon_l with such patterns is affected, though no network-facing application impact was known at publication. No public proof of concept or in-the-wild exploitation has been reported, and the issue is not on the CISA KEV list.

Do: Apply your distribution's patched glibc packages (e.g., Ubuntu USN-8737-1 / USN-8737-2) or upgrade to a glibc release newer than 2.44, then restart long-running services so they relink against the fixed library. Audit internally developed software for calls to strfmon/strfmon_l with right-justified width padding, especially where monetary format strings or field widths derive from user input, and sanitize or cap those inputs in the interim. Since no network-facing impact is known, prioritize this as routine patching rather than emergency response, but track vendor advisories for newly identified vulnerable applications.

7.7
  • GNU Project GNU C Library (glibc) 2.38 to 2.44
massglibc ships on essentially every Linux system (plausibly >1 billion installations), but the set of applications with a vulnerable strfmon call path is unknown…
CVE-2026-19542
Stack Buffer Overflow in GNU C Library (glibc) tdelete on Deep Trees

A stack-based buffer overflow (CWE-121) exists in the tdelete function of the GNU C Library versions 2.1 through 2.44, where two rebalancing branches push an entry onto an internal parent-node stack without checking capacity, writing one pointer past the end of an alloca-allocated array. Triggering it requires deleting a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree of at least a million nodes, meaning an attacker would need to drive a very large number of insertions and deletions through an application that uses tsearch/tdelete. The written value is a pointer into a tree node and is not directly attacker controlled, so the most likely outcome is an application crash (low confidentiality/integrity/availability impact per the CVSS 5.6 rating). No affected application in common Linux distributions has been identified, significantly limiting real-world attack surface. No public proof of concept exists and the flaw is not in the CISA KEV catalog.

Do: Apply distribution security updates for glibc as they ship (Ubuntu has published USN-8737-1 and USN-8737-2 covering this issue) rather than waiting for a targeted exploit. Audit any in-house or third-party applications that use tsearch/tdelete on attacker-influenced data, and confirm they cannot accumulate trees of a million or more nodes. Because the written value is not attacker controlled, the primary risk is denial of service via crash, so prioritize patching on long-running services that maintain large search trees.

5.6
  • GNU Project GNU C Library (glibc) 2.1 through 2.44
masshundreds of millions of Linux systems (glibc ships as the default C library on nearly all major distributions), though realistically exploitable applications…
CVE-2026-33007
A NULL pointer dereference in the mod_authn_socache in Apache HTTP Server 2.4.66 and earlier allows an unauthenticated remote user to crash a child process in a

A NULL pointer dereference in the mod_authn_socache in Apache HTTP Server 2.4.66 and earlier allows an unauthenticated remote user to crash a child process in a caching forward proxy configuration. Users are recommended to upgrade to version 2.4.67, which fixes this issue.

NVD description · AI analysis pending
5.3<1%
  • apache http server
CVE-2026-3644
The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete.

The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().

NVD description · AI analysis pending
6.0<1%
  • python python
CVE-2026-62291
Heap out-of-bounds write/read in libheif image sequence decode and re-encode (≤ 1.23.0)

libheif, a widely used open-source HEIF/AVIF decoder and encoder, fails to validate that an auxiliary alpha plane's dimensions match the main frame when decoding image sequences: Track_Visual::decode_next_image_sample() passes an inconsistent image downstream, and during re-encoding unc_encoder_component_interleave::encode_tile() allocates its buffer using the primary dimensions while copying each component using its actual plane dimensions, causing an attacker-controlled heap out-of-bounds write (and, with the inverse mismatch, an out-of-bounds read). The flaw is triggered by decoding a crafted image sequence (a 2x2 primary plane with a 256x256 alpha plane is a demonstrated trigger) in a normal decode-and-re-encode workflow, so an attacker gains heap corruption that can crash the application (DoS) and potentially enable memory-corruption exploitation with limited confidentiality, integrity, and availability impact per the CVSS scoring. Any application or system that decodes untrusted HEIF/AVIF image sequences with libheif 1.23.0 or earlier is affected, including Linux distributions that ship the library, as confirmed by Ubuntu security notice USN-8774-1. No public proof-of-concept is known, the flaw is not in CISA KEV, and EPSS estimates only a 0.1% probability of exploitation within 30 days, so no exploitation is currently known.

Do: Upgrade libheif to version 1.23.1, or apply the distro update provided in Ubuntu USN-8774-1 (and equivalent updates in other distributions that package libheif). Until patched, avoid processing untrusted HEIF/AVIF image sequences in tools that decode and re-encode/transcode images with libheif (viewers, thumbnailers, transcoders, ImageMagick/vips-style pipelines that link it). Inventory systems and applications for linked libheif builds to confirm they receive the fixed version.

5.3<1%
  • libheif (strukturag) libheif 1.23.0 and earlier (fixed in 1.23.1)
  • Canonical Ubuntu libheif packages supported Ubuntu releases shipping libheif 1.23.0 or earlier (fixes issued in USN-8774-1)
massplausibly millions of installed systems carry the affected library (distro-packaged), though only sequence decode/re-encode workflows are reachable
CVE-2026-62377
Reachable assertion / empty-map crash (DoS) in libheif HEIF sequence handling

libheif, a widely used HEIF/AVIF decoder and encoder library, mishandles crafted HEIF sequences that are accepted by heif_context_read_from_memory() but contain no registered sequence tracks. A subsequent call to heif_context_get_track(ctx, 0) reaches HeifContext::get_track() in context.cc, where assert(has_sequence()) executes before normal error handling, so assert-enabled builds abort instead of letting the wrapper in heif_sequences.cc return null; in release builds the track_id-zero path dereferences m_tracks.begin()->second on an empty map, which is undefined behavior and typically crashes the process. An attacker who can supply a malicious HEIF/AVIF file to an application using these documented public APIs can therefore cause a denial of service (CVSS C:N/I:N/A:L, with user interaction required to open the file). Any application, service, or distribution package linking libheif 1.23.0 or earlier and parsing untrusted media through these APIs is affected; Ubuntu has issued USN-8774-1 for its libheif packages. There is no known public PoC, the issue is not in CISA KEV, and EPSS estimates only a ~0.3% chance of exploitation in the next 30 days.

Do: Upgrade libheif to version 1.23.1 or later, and on Ubuntu apply the package updates from USN-8774-1; rebuild statically linked applications against the patched library. Applications using the sequence APIs should additionally validate that a context contains tracks before calling heif_context_get_track(), and treat untrusted HEIF/AVIF inputs (e.g., uploads, thumbnails) as suspect until patched.

4.3<1%
  • strukturag (libheif project) libheif 1.23.0 and earlier (fixed in 1.23.1)
  • Canonical Ubuntu libheif packages affected packages per USN-8774-1 (see the notice for fixed package versions)
massmillions of Linux installations ship the library (packaged in Ubuntu per USN-8774-1 and common in image/thumbnailing stacks), though only apps parsing…
CVE-2026-69247
cryptography is a package designed to expose cryptographic primitives and recipes to Python developers.

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. From 44.0.0 until 50.0.0, pkcs7_decrypt_der, pkcs7_decrypt_pem, and pkcs7_decrypt_smime reported the outcome of decrypting a RecipientInfo's encryptedKey in several distinguishable ways, one of which disclosed the exact length recovered from the RSA operation. The same distinction was also observable by timing. An application that decrypts attacker-supplied EnvelopedData and reflects the outcome gives the attacker a Bleichenbacher oracle against the content-encryption key. Decryption ran as RSA PKCS#1 v1.5 decrypt of encryptedKey, build an AES cipher from the result, then AES-CBC decrypt and PKCS#7 unpad. Invalid RSA padding, a valid padding with a bad key length, a correct length with a wrong key, and the real key each failed or succeeded differently. Case 1 is reachable only where the linked library lacks implicit rejection: OpenSSL 3.0 and 3.1, LibreSSL, and BoringSSL. Exploitation requires a service that auto-decrypts untrusted EnvelopedData matching the victim certificate and answers adaptively at high volume, such as an S/MIME gateway or mail filter. This issue is fixed in 50.0.0.

NVD description · AI analysis pending
8.2<1%