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CVE-2026-34486: Apache Tomcat EncryptInterceptor Fail-Open Bypass

Technical analysis shows CVE-2026-34486 is a one-line fail-open regression in Tomcat Tribes enabling unauthenticated RCE via Java deserialization.

CVE-2026-34486 is a fail-open regression in Tomcat's Tribes EncryptInterceptor, introduced while fixing the CVE-2026-29146 padding-oracle flaw; Apache rated it Important and NVD scores it 7.5 High. Decryption failures are now forwarded to an unfiltered ObjectInputStream, and public PoC repositories demonstrate unauthenticated RCE on default port 4000 when clustering, the EncryptInterceptor, a reachable receiver and deserialization gadgets are all present. Affected releases 9.0.116, 10.1.53 and 11.0.20 are fixed in 9.0.117, 10.1.54 and 11.0.21; Tomcat 8.5 is unaffected.

Attackers Chain Two PaperCut Flaws to Execute Code Without Authentication

Attackers chain PaperCut NG/MF flaws CVE-2026-81578 and CVE-2026-82078 for unauthenticated RCE; exploitation observed and a second emergency patch issued.

Two flaws in PaperCut NG and MF — CVE-2026-81578 (CVSS 8.8, improper access control enabling auth bypass) and CVE-2026-82078 (CVSS 9.4, unsafe dynamic class loading) — are being chained for unauthenticated remote code execution. Huntress observed limited exploitation on two customer environments, including Base64-encoded commands, 'whoami & ver' fingerprinting, SimpleHelp execution, and AnyDesk installation for persistence. PaperCut released a second emergency patch for v24, v25, and v26, but watchTowr reports additional patch bypasses may still affect the latest version. Shared IoCs include crafted jdbc strings in server.log and attacker-written .class/.cmd files.

The Hacker News · 14d agoExploit / PoC in the wildCVE-2026-82078CVE-2026-815781

PaperCut Replaces Emergency Patches With Fixes for Two Actively Exploited Flaws

PaperCut shipped maintenance releases replacing emergency patches for two actively exploited flaws abused in AI-assisted attacks on 395 organizations.

PaperCut released PaperCut NG/MF versions 26.0.5, 25.0.13 and 24.1.10, superseding Emergency Patch Releases 1-3 for CVE-2026-81578 and CVE-2026-82078, which enable authentication bypass and arbitrary code execution on susceptible instances. GreyNoise and Blackpoint Cyber reported a suspected Russian-speaking actor weaponizing both flaws against at least 395 organizations in 48 countries, concentrated in the U.S. education sector. The campaign used hundreds of AI agents powered by OpenAI's Codex harness and a DeepSeek model, originating from IP 45.142.193.132, and avoided organizations in Russia, China, Hong Kong, Thailand and Iran.

The Hacker Newsupdated · 5d agofirst · 5d agoExploit / PoC in the wild 7 sourcesCVE-2026-81578CVE-2026-820781

Attackers Hijack MikroTik Routers Through Internet-Exposed SSH Without Authentication

CERT Polska warns attackers exploit internet-exposed MikroTik SSH for unauthenticated full admin control; attacks observed since at least September 2.

CERT Polska warned on September 5 that attackers exploit MikroTik routers with internet-reachable SSH to gain full administrative control without authentication, calling the two-flaw combination 'MikroTrick'. Successful attacks date to at least September 2; no victim count or attacker identity was disclosed. MikroTik shipped fixed RouterOS releases: 6.49.21, 7.23.4 (with 7.23.5 fixing an IPv6 DHCP regression), 7.24.2, and 7.25beta3. CERT recommends immediate updates, checking for unauthorized configuration changes, and restricting SSH, WWW/WWW-SSL, and bandwidth-test services on unpatched devices.

The Hacker News · 10d agoExploit / PoC in the wild

Attackers plant remote access tools on compromised PaperCut servers

Attackers chained two PaperCut NG/MF zero-days for unauthenticated access, installing SimpleHelp and AnyDesk remote access tools on compromised servers.

An ongoing campaign exploits chained zero-days CVE-2026-81578 (improper access control) and CVE-2026-82078 (unsafe dynamic class loading) in internet-facing PaperCut NG and MF Application Servers, enabling authentication bypass and arbitrary Java bytecode execution. Post-compromise activity includes user and domain enumeration, payload download from sendit.sh, and silent installation of SimpleHelp and AnyDesk for redundant remote access; Defused observed CVE-2026-81578/CVE-2026-82078 exploit activity in honeypots since August 29, including data theft via Derby database dumps. Emergency patches were released August 28 and August 30, but 47% of roughly 2,500 PaperCut installs tracked by Huntress run v23 or older, for which no patch is available.

Help Net Security · 14d agoExploit / PoC in the wildCVE-2026-81578CVE-2026-820781