Previously patched Citrix NetScaler flaw exploited in the wild (CVE-2026-8452)

CVE-2015-3246 is a race condition in Red Hat's libuser, the user-management library used by utilities that modify system accounts, that can cause corruption of the /etc/passwd file during concurrent account updates. An authenticated local user who triggers the race — typically by racing account-modification operations against one another — can desynchronize or corrupt the passwd file. Successful exploitation yields either a denial-of-service condition on the host or, in the privilege-escalation case, elevated (root-level) access by manipulating entries in /etc/passwd. Any Red Hat system shipping the vulnerable libuser library is affected, with risk concentrated on multi-user servers where untrusted local accounts exist. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-08-26, indicating it is being exploited in the wild, and EPSS assigns it an 8.8% probability of exploitation within 30 days (95th percentile); ransomware use is unknown and no public proof-of-concept is cataloged.

Do: Update libuser to the fixed packages provided in Red Hat's security advisories across all RHEL/Fedora systems, prioritizing multi-user servers and any asset with untrusted local accounts, in line with CISA BOD 26-04 requirements (apply vendor mitigations or discontinue use of the product where mitigation is unavailable). Because exploitation requires local credentials, review which systems expose local login to non-administrators and check the integrity of /etc/passwd for signs of tampering. Confirm the patched library is active after update and monitor for further KEV-driven deadlines.

CVE-2015-5287 is a privilege escalation flaw in Red Hat's Automatic Bug Reporting Tool (ABRT) in which a local user with certain permissions can gain elevated privileges via a symlink attack against a file with a predictable name. Exploitation requires local access to an affected system; an attacker who triggers the flawed file-handling behavior can elevate their privileges on that machine. It affects deployments running ABRT, which ships by default with Red Hat Enterprise Linux and related distributions, including systems that may now be end-of-life or end-of-service. CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2026-08-26, indicating exploitation has been observed in the wild, though no public proof-of-concept is known and ransomware use is unknown. EPSS estimates a 5.0% probability of exploitation within 30 days (92nd percentile).

Do: Prioritize remediation per CISA BOD 26-04: inventory systems running ABRT (including EoL/EoS hosts), apply the updated abrt packages from Red Hat's security advisories, and migrate unsupported releases to a supported version. Where patching is not feasible, restrict local access to affected systems or disable/remove ABRT if it is not needed. Assess each asset's internet exposure and local user access, and triage per CISA's Forensics Triage Requirements.

CVE-2019-1068 is a remote code execution vulnerability in Microsoft SQL Server caused by improper handling of the processing of internal functions (CWE-20, improper input validation). An attacker who can reach SQL Server over the network with low-privileged credentials can trigger the flawed code path and execute arbitrary code, gaining high confidentiality, integrity, and availability impact on the database host. Any organization running affected Microsoft SQL Server versions — including SQL Server 2016 and SQL Server 2017 — is affected. The flaw carries a high EPSS score (52.8% probability of exploitation within 30 days, 99th percentile) and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-26, with headlines reporting it being exploited in active attacks. No public proof-of-concept is known, but the in-the-wild exploitation documented by CISA makes patching urgent; the fix shipped in Microsoft's July 2019 Patch Tuesday security updates.

Do: Apply Microsoft's July 2019 security updates (cumulative updates) for SQL Server 2016 and SQL Server 2017 as directed in the vendor advisory, and inventory all SQL Server instances — especially those reachable on TCP 1433 from the internet — prioritizing exposed or low-privilege-accessible instances. Given the KEV listing, CISA's BOD 26-04 requires patching per vendor instructions (or discontinuing use if mitigation is unavailable) on a prioritized timeline; restrict network access to SQL Server and confirm no unexpected low-privileged accounts or unusual process activity on database hosts as a triage check.

Ajax.NET Professional (distributed as the ajaxpro.2 package) is vulnerable to insecure deserialization (CWE-502): it deserializes arbitrary .NET classes supplied by the client without validating which types may be instantiated. Because AjaxPro exposes HTTP endpoints for browser-to-server AJAX calls, a remote, unauthenticated attacker can send a crafted serialized payload to any reachable AjaxPro endpoint and abuse .NET deserialization gadget chains to execute code on the server. Successful exploitation yields full remote code execution with high impact on confidentiality, integrity, and availability (CVSS 3.1 score of 9.8, network vector, no privileges or user interaction required). Any application running any version of ajaxpro.2 / Ajax.NET Professional is affected; the provided data specifies no fixed version, so defenders must rely on vendor guidance for patched releases. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-08-26, carries an EPSS 30-day exploitation probability of 83.6%, has public PoC code available, and Talos Intelligence reporting links it to the Chinese-speaking threat actor UAT-10147, which deploys the SPECTRE malware with an EDR bypass and a Linux rootkit in post-compromise operations.

Do: Inventory your ASP.NET estate for AjaxPro usage (web.config references, AjaxPro HTTP handlers) and prioritize any internet-facing instance for remediation. Upgrade ajaxpro.2 to the latest vendor release per vendor instructions — the provided data specifies no fixed version — or, if patching is not immediately possible, restrict or block access to AjaxPro endpoints from the internet. Because the flaw is on CISA's KEV under BOD 26-04, apply mitigations within the required timeline and hunt exposed servers for post-compromise tooling, as Talos reports UAT-10147 deploying SPECTRE with an EDR bypass and a Linux rootkit.

CVE-2022-0995 is an out-of-bounds (OOB) memory write in the Linux kernel's watch_queue event notification subsystem (CWE-787) that can overwrite parts of kernel state. A local user can trigger it through the watch_queue interface, for example by supplying a crafted event filter definition, causing the kernel to write beyond allocated memory when event notifications are processed. Successful exploitation may allow the local user to gain privileged (kernel/root) access or crash the system, yielding high impact on confidentiality, integrity, and availability (CVSS 3.1: 7.8, local attack vector). Affected systems include mainstream Linux kernels (Fedora is explicitly listed) and NetApp HCI appliance firmware products that ship the affected kernel. The flaw is confirmed exploited in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-26, two public proof-of-concepts are available, and EPSS puts 30-day exploitation probability at 9.5% (95th percentile), though ransomware use is unconfirmed.

Do: Apply updated kernels from your distribution or vendor (Fedora kernel updates; NetApp fixes are delivered via the HCI firmware updates in its security advisory) and prioritize internet-exposed, multi-user hosts per CISA BOD 26-04, including the required forensics triage checks. Because exploitation requires local access, restrict untrusted local code execution and shell access on unpatched systems, and hunt for signs of local privilege escalation on high-exposure hosts. After remediation, verify the patched kernel package is installed and that the running kernel has actually been booted into the fixed version.

CVE-2026-8452 is a memory buffer overflow (CWE-119) in Citrix NetScaler ADC and NetScaler Gateway that applies when the appliance is configured as a Gateway (SSL VPN, ICA Proxy, CVPN, or RDP Proxy) or as an AAA virtual server. The flaw is reachable over the network without authentication (CVSS 4.0: AV:N/PR:N), so an unauthenticated attacker can trigger it remotely. Successful exploitation causes unpredictable or erroneous appliance behavior and denial of service, and the high confidentiality score suggests possible disclosure of memory contents; some reporting suggests pre-authentication remote code execution may be possible, though the vendor description emphasizes DoS. Organizations running affected NetScaler appliances in a Gateway or AAA role — a very common configuration for remote access to Citrix virtual apps and desktops — are potentially exposed. The flaw was added to CISA's KEV catalog on 2026-08-26 and is reported as exploited in the wild, with headlines noting the flaw was already patched before exploitation was confirmed.

Do: Upgrade NetScaler ADC and Gateway to the fixed releases identified in Citrix security advisory AV26-645 (Update 3); no fixed version numbers were included in this data, so consult the advisory directly. Prioritize any appliance with an internet-exposed Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server, and given the KEV listing and reports of exploitation, perform log and forensics review for signs of prior compromise per CISA's Forensics Triage Requirements — federal agencies must comply with BOD 26-04 timelines. Where patching cannot happen immediately, restrict or disable exposed Gateway/AAA configurations as an interim mitigation.