VulnerabilityPublished 11 Sep 2026Updated 5 Oct 2026

CVE-2026-89490: Linux kernel · ocfs2: fix readdir position truncation on 32-bit kernels

Affects Linux kernelSource GCVE Database

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: 0.1% chance of exploitation in 30 days – higher than 7% 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 is available that corrects the masking operation by casting the operand to 64-bit before applying it. Users should update to a Linux kernel version that includes this fix. Since this is a kernel-level bug, applying the official kernel patch or upgrading to a fixed kernel version is the recommended remediation.

Description

A vulnerability in the Linux kernel's ocfs2 filesystem code causes incorrect directory read positions on 32-bit kernels when directories exceed 4 GiB. This leads to readdir() calls re-enumerating directory entries indefinitely past the 4 GiB boundary. The issue arises from a 32-bit mask being applied to a 64-bit position value, truncating the high bits. 64-bit kernels are not affected. The flaw has been fixed by properly casting the mask operand to 64-bit.

Impact

On affected 32-bit Linux kernels, reading directories larger than 4 GiB with readdir() can cause the directory position to reset incorrectly, leading to repeated enumeration of directory entries. This can cause performance degradation or application-level issues when processing large directories. There is no indication of privilege escalation or data corruption from this bug.

Summary

The Linux kernel's ocfs2 filesystem had a bug in ocfs2_dir_foreach_blk_el() where the directory cookie position (ctx->pos) was rebuilt using a mask derived from sb->s_blocksize. On 32-bit kernels, sb->s_blocksize is 32-bit unsigned long, so the mask was zero-extended to 64 bits, clearing the high 32 bits of the 64-bit ctx->pos. This caused the readdir position to reset after crossing the 4 GiB boundary, resulting in indefinite re-enumeration of directory entries for large directories. The fix casts the mask operand to loff_t (64-bit) before the AND operation, preserving the full 64-bit position. 64-bit kernels are unaffected by this issue.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Oct 2026, 01:27 UTC

Technical details

References

Community reviews

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