VulnerabilityPublished 11 Sep 2026Updated 5 Oct 2026

CVE-2026-89757: Linux kernel · mm/mglru: fix and remove redundant unevictable folio handling

Affects Linux kernelSource GCVE Database

Authoritative record:CVE-2026-89757

Not known to be exploited.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 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 26.04 LTSlinux`pkg:deb/ubuntu/linux?arch=source&distro=resolute`Other threats	Affected 6.17.0-5.5 – 7.0.0-38.38 23 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=resolute`Other threats	Affected 6.17.0-1003.3 – 7.0.0-1017.17 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resolute`Other threats	Affected 7.0.0-1003.3 – 7.0.0-1016.16 9 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 13 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gke`pkg:deb/ubuntu/linux-gke?arch=source&distro=resolute`Other threats	Affected 7.0.0-1002.3 – 7.0.0-1008.9 6 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 by removing the buggy shortcut in sort_folio() and aligning the handling of unevictable folios with classical LRU behavior. Users should apply the official kernel updates containing this fix. No additional mitigation actions are necessary as the fix addresses the root cause and there are no known active exploits.

Description

A vulnerability in the Linux kernel's memory management subsystem (mm/mglru) involves a buggy shortcut in the sort_folio() function that mishandles unevictable folios. This causes incorrect accounting of locked memory pages, leading to inflated mlocked counts and folios remaining unevictable longer than intended. The issue also risks unexpected behavior due to improper handling of LRU flags during concurrent operations. The vulnerability has been fixed by changing the handling to align with classical LRU behavior, removing the buggy shortcut.

Impact

The vulnerability causes incorrect memory management accounting in the Linux kernel, specifically inflated mlocked counts and folios remaining unevictable longer than intended. This can lead to memory management inconsistencies and unexpected behavior during memory compaction or isolation operations. There is no indication of direct security exploitation or data compromise, and no known exploits in the wild have been reported.

Summary

The Linux kernel vulnerability CVE-2026-89757 is due to a faulty shortcut in the sort_folio() function within the mm/mglru subsystem. The shortcut incorrectly handles unevictable folios by not properly initializing the mlock_count field, which can be poisoned with a stale value (LIST_POISON2). This causes __munlock_folio() to incorrectly detect a non-zero lock count and skip clearing the PG_mlocked flag, leaving folios unevictable and inflating mlocked accounting until the folio is freed. Additionally, the shortcut calls lru_gen_del_folio() while PG_lru is still set, allowing concurrent folio_test_clear_lru() calls to succeed on folios already removed from generation lists, potentially causing unexpected behavior. The fix removes the shortcut and treats unevictable folios as common folios, letting the generic shrink path handle them, restoring classical LRU behavior without performance impact.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Oct 2026, 03:42 UTC

Technical details

References

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