VulnerabilityPublished 28 Oct 2026

CVE-2026-99175: Linux kernel · fsnotify: prevent mark additions during connector teardown

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in 952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

Patch: Available – fixed in 952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1, 472589eacdf10b5f9bd10b333957ed5291b2544b, 36ebddca56b9d8993d6dc984fdecc748ee1f5e06

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.

What to do

Upgrade Linux kernel to 952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1, 472589eacdf10b5f9bd10b333957ed5291b2544b or 36ebddca56b9d8993d6dc984fdecc748ee1f5e06.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 6b3f05d24d355f50f3d9814304650fcab0efb482, < 952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1	Fixed in 952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1
LinuxLinux	Affected ≥ 6b3f05d24d355f50f3d9814304650fcab0efb482, < 472589eacdf10b5f9bd10b333957ed5291b2544b	Fixed in 472589eacdf10b5f9bd10b333957ed5291b2544b
LinuxLinux	Affected ≥ 6b3f05d24d355f50f3d9814304650fcab0efb482, < 36ebddca56b9d8993d6dc984fdecc748ee1f5e06	Fixed in 36ebddca56b9d8993d6dc984fdecc748ee1f5e06
LinuxLinux	Affected =4.12	Fixed in–
Debiandebian/linux`pkg:deb/debian/linux`Other threats	Affected =4.12	Fixed in–

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

Description

In the Linux kernel, the following vulnerability has been resolved: fsnotify: prevent mark additions during connector teardown fsnotify_destroy_marks() keeps a reference to its current mark while it drops conn->lock to destroy the mark. This stabilizes the forward-walk cursor, but does not prevent a new mark from being inserted before it. For example, an inotify watch re-added after IN_IGNORED sorts before the old, detached mark for the same group. The walk can miss the replacement and then detach the entire connector from the object. The replacement is still on its group's marks_list and, for inotify, in the watch IDR. The group mutex no longer protects the connector's object from disappearing. An unprivileged fdinfo read racing the final detach can consequently call igrab(NULL): BUG: KASAN: null-ptr-deref in igrab+0x24/0x100 Write of size 4 at addr 0000000000000148 Call Trace: igrab+0x24/0x100 inotify_show_fdinfo+0x1dc/0x5e0 seq_show+0x397/0x690 Set a DESTROYING flag under conn->lock before starting the walk, and reject new marks on that connector with -ENOENT. The existing add-mark error paths undo the temporary group-list entry and the backend's watch allocation. Do not wait for teardown while holding the group mutex, which the destroyer needs. Once the old connector is detached, an add can install a fresh connector as before. This closes the insertion race for all object types using the common connector teardown, without changing the mark reference or SRCU lifetime rules.

References

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