VulnerabilityPublished 28 Oct 2026

CVE-2026-99203: Linux kernel · pipe: preserve existing fasync readers on writer setup failure

Source GCVE Database

Authoritative record:CVE-2026-99203

Not known to be exploited · fixed in 2259809e5b7043c4ba20af7b14ba3e471cf55521 : patch Linux kernel soon.

Data as of 28 Oct 2026, 13:30 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Patch: Available – fixed in 2259809e5b7043c4ba20af7b14ba3e471cf55521, 40bb03d3ea6f6a915218508819ecc4d7a7fa260d, 4c42ce499ce4b1c787e61082e3b13df4f30c4eaa

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 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.

ghsa-j875-7x9h-g92w

What to do

Upgrade Linux kernel to 2259809e5b7043c4ba20af7b14ba3e471cf55521, 40bb03d3ea6f6a915218508819ecc4d7a7fa260d or 4c42ce499ce4b1c787e61082e3b13df4f30c4eaa.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 76398425bb06b07cc3a3b1ce169c67dc9d6874ed, < 2259809e5b7043c4ba20af7b14ba3e471cf55521	Fixed in 2259809e5b7043c4ba20af7b14ba3e471cf55521
LinuxLinux	Affected ≥ 76398425bb06b07cc3a3b1ce169c67dc9d6874ed, < 40bb03d3ea6f6a915218508819ecc4d7a7fa260d	Fixed in 40bb03d3ea6f6a915218508819ecc4d7a7fa260d
LinuxLinux	Affected ≥ 76398425bb06b07cc3a3b1ce169c67dc9d6874ed, < 4c42ce499ce4b1c787e61082e3b13df4f30c4eaa	Fixed in 4c42ce499ce4b1c787e61082e3b13df4f30c4eaa
LinuxLinux	Affected =2.6.30	Fixed in–

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel to preserve existing asynchronous reader registrations on writer setup failure, preventing the use-after-free condition. Users should apply the official kernel updates that include this fix once available.

Description

A vulnerability in the Linux kernel's pipe implementation could lead to a use-after-free condition in the send_sigio() function. This occurs due to improper handling of asynchronous notification registrations when a writer setup fails, potentially causing a later pipe notification to dereference freed memory. The issue arises from the removal of a pre-existing reader entry during error handling, which clears asynchronous flags incorrectly while the writer entry remains registered.

Impact

This vulnerability can cause a kernel slab use-after-free error, potentially leading to kernel memory corruption or system instability. It is triggered by unprivileged memory pressure conditions, indicating that local unprivileged users could exploit this flaw to cause denial of service or possibly escalate privileges through kernel memory corruption. However, no known exploits in the wild have been reported.

References

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