VulnerabilityPublished 17 Sep 2026Updated 23 Sep 2026

CVE-2026-90339: Linux kernel · powerpc/syscall: Fix syscall skip handling for seccomp and ptrace

Affects Linux kernelSource GCVE Database

Not known to be exploited.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 24.04 LTSlinux-aws-6.14`pkg:deb/ubuntu/linux-aws-6.14?arch=source&distro=noble`Other threats	Affected 6.14.0-1007.7~24.04.1 – 6.14.0-1018.18~24.04.1 11 affected builds	Fixed in–
Ubuntu 24.04 LTSlinux-aws-6.17`pkg:deb/ubuntu/linux-aws-6.17?arch=source&distro=noble`Other threats	Affected 6.17.0-1005.5~24.04.2 – 6.17.0-1020.20~24.04.1 10 affected builds	Fixed in–
Ubuntu 24.04 LTSlinux-azure-6.11`pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=noble`Other threats	Affected 6.11.0-1008.8~24.04.1 – 6.11.0-1018.18~24.04.1 7 affected builds	Fixed in–
Ubuntu 24.04 LTSlinux-azure-6.14`pkg:deb/ubuntu/linux-azure-6.14?arch=source&distro=noble`Other threats	Affected 6.14.0-1010.10~24.04.1 – 6.14.0-1017.17~24.04.1 5 affected builds	Fixed in–
Ubuntu 24.04 LTSlinux-azure-6.17`pkg:deb/ubuntu/linux-azure-6.17?arch=source&distro=noble`Other threats	Affected 6.17.0-1008.8~24.04.1 – 6.17.0-1022.22 10 affected builds	Fixed in–
Ubuntu 24.04 LTSlinux-azure-fde-6.14`pkg:deb/ubuntu/linux-azure-fde-6.14?arch=source&distro=noble`Other threats	Affected 6.14.0-1012.12~24.04.1 – 6.14.0-1017.17~24.04.1 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel. Users should apply the updated kernel versions that include this patch to ensure correct syscall handling on PowerPC architectures with seccomp and ptrace. No additional mitigation is required beyond updating to a fixed kernel version.

Description

A vulnerability in the Linux kernel's PowerPC syscall handling was fixed to correctly manage return values set by seccomp and ptrace. The issue involved improper handling of a sentinel return value (-1) used to indicate intercepted syscalls, which caused erroneous overwriting of the intended return value. The fix introduces a thread flag to track explicit return value updates, ensuring correct syscall execution suppression and proper handling of all seccomp actions. This affects multiple specific Linux kernel versions used in various Ubuntu LTS releases.

Impact

The vulnerability could cause the Linux kernel to incorrectly overwrite return values for intercepted syscalls on PowerPC systems, potentially disrupting seccomp and ptrace functionality. This may lead to improper syscall handling and unexpected behavior in processes using these security mechanisms. The fix ensures that explicitly supplied return values from seccomp or ptrace are honored, maintaining correct syscall interception and return value semantics.

Summary

The Linux kernel on PowerPC architectures had a vulnerability in syscall handling related to seccomp and ptrace interception. When GENERIC_ENTRY was enabled, syscall_enter_from_user_mode() returned -1 as a sentinel indicating interception and a preset return value. However, system_call_exception() did not handle this sentinel correctly, treating -1UL as an out-of-range syscall number and overwriting the return value with -ENOSYS. The naive fix was ambiguous because a legitimate syscall(-1) call also produces -1L, risking silent discard of injected return values. The implemented fix adds a thread flag set by syscall_set_return_value() to indicate an explicit return value update. system_call_exception() checks and clears this flag, returning the preset value directly and suppressing syscall execution. This fix covers all seccomp actions correctly and applies to both ppc32 and ppc64 architectures without conditional compilation.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Oct 2026, 22:28 UTC

Technical details

References

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