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CVE-2026-89595· NVD / CVE Program· CNA Linux

fsnotify: Fix stale object mask after concurrent mark updates

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 27d172b60eeca5c8fd51b246f9fb959067cf102b, 2f09f08d602647fc4e328fc27ecb4c3008d10338, 343ae18e960f6c5f1d34d58a69750c62cd463228.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 27d172b60eeca5c8fd51b246f9fb959067cf102b, 2f09f08d602647fc4e328fc27ecb4c3008d10338, 343ae18e960f6c5f1d34d58a69750c62cd463228 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: fsnotify: Fix stale object mask after concurrent mark updates When a mark gets a new event bit, fanotify and inotify may avoid recalculating the object mask if the cached aggregate already contains that bit. This is racy with a recalculation triggered by a concurrent update to another mark on the same connector. The concurrent scan can read the mark before the new bit is added, while the updater reads the old aggregate before that scan publishes its result. The updater then skips recalculation and the scan publishes a mask without the bit, leaving the object mask stale after both updates complete. This can be reproduced with two fanotify groups watching the same inode: one thread removes FAN_MODIFY from one existing mark while another thread adds FAN_MODIFY to the other mark. After both fanotify_mark() calls return, writes can fail to produce FAN_MODIFY for the group whose mark now contains the bit. This was reproduced on an unmodified v6.12.95 kernel. The equivalent inotify interleaving loses IN_MODIFY events. For normal fanotify additions, recalculate whenever the raw mark mask changes. The normal mask is not cleared asynchronously, so an unchanged addition cannot introduce missing interest. Always recalculate ignore-mask updates because FS_MODIFY handling may clear the ignore mask without taking mark->lock, making snapshot comparisons unreliable. Always recalculate after updating an existing inotify watch. Its replace path temporarily sets mark->mask to zero, so a concurrent scan can observe zero even when the old and final masks are equal. Assigning the replacement mask directly would avoid the transient zero, but existing-watch updates are infrequent, so unconditional recalculation is simpler.

—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 11th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.31affected
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before 27d172b60eeca5c8fd51b246f9fb959067cf102baffected · git
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before 2f09f08d602647fc4e328fc27ecb4c3008d10338affected · git
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before de75382d6e354b2b055df4896d12a91969f12090affected · git
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before 343ae18e960f6c5f1d34d58a69750c62cd463228affected · git
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before 92289e66639f62abc754c6f3bce5ead7e98e4ee2affected · git
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before 947400af98b9e63841929d079a2c3ea0a8ba227baffected · git
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before ac8d8b599d466a129122bded77db3d0f8b96b461affected · git
    • 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and later · before e422777fdd4746de1109575c51e65038d4c5c1beaffected · git
    • before 2.6.31not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-89593Sep 11, 2026 · hugetlb: only adjust reservation during unmapping if mapcount is 0
    28Monitor
  • ← EarlierCVE-2026-89594Sep 11, 2026 · hsi: omap_ssi_core: fix missing DMA mask setup for SSI controller device
    31Monitor
  • Later →CVE-2026-89596Sep 11, 2026 · forcedeth: fix off-by-one when saving/restoring non-PCI config space
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux27d172b60eeca5c8fd51b246f9fb959067cf102bVendor (CNA)
Linux Linux2f09f08d602647fc4e328fc27ecb4c3008d10338Vendor (CNA)
Linux Linux343ae18e960f6c5f1d34d58a69750c62cd463228Vendor (CNA)
Linux Linux92289e66639f62abc754c6f3bce5ead7e98e4ee2Vendor (CNA)
Linux Linux947400af98b9e63841929d079a2c3ea0a8ba227bVendor (CNA)
Linux Linuxac8d8b599d466a129122bded77db3d0f8b96b461Vendor (CNA)
Linux Linuxde75382d6e354b2b055df4896d12a91969f12090Vendor (CNA)
Linux Linuxe422777fdd4746de1109575c51e65038d4c5c1beVendor (CNA)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records