VulnerabilityPublished 25 Sep 2026Updated 19 Oct 2026

CVE-2026-97549: Linux kernel · xfs: fix under-reservation of blocks when repairing sf directories

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in b950e84acd072ac648ace4fea53c0b1212da4b2c : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

Severity

High

Rated High by Threat Radar's AI analysis · 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.
Patch: Available – fixed in b950e84acd072ac648ace4fea53c0b1212da4b2c, b8f46ca5cbd629ffb91489ad7f970b3837835b0a, 996cce0c422b66a0e8b1a99505f896b0669ee5b6 +1

Exploitation evidence

Disclosed: evidence found.
CVE published 25 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

Upgrade Linux kernel to b950e84acd072ac648ace4fea53c0b1212da4b2c, b8f46ca5cbd629ffb91489ad7f970b3837835b0a, 996cce0c422b66a0e8b1a99505f896b0669ee5b6 or 4d3c07591534517c633945c8d8e6526f10e3fabc.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 629fdaf5f5b1b7f7107ed4de04e0991a99501ced, < b950e84acd072ac648ace4fea53c0b1212da4b2c	Fixed in b950e84acd072ac648ace4fea53c0b1212da4b2c
LinuxLinux	Affected ≥ 629fdaf5f5b1b7f7107ed4de04e0991a99501ced, < b8f46ca5cbd629ffb91489ad7f970b3837835b0a	Fixed in b8f46ca5cbd629ffb91489ad7f970b3837835b0a
LinuxLinux	Affected ≥ 629fdaf5f5b1b7f7107ed4de04e0991a99501ced, < 996cce0c422b66a0e8b1a99505f896b0669ee5b6	Fixed in 996cce0c422b66a0e8b1a99505f896b0669ee5b6
LinuxLinux	Affected ≥ 629fdaf5f5b1b7f7107ed4de04e0991a99501ced, < 4d3c07591534517c633945c8d8e6526f10e3fabc	Fixed in 4d3c07591534517c633945c8d8e6526f10e3fabc
LinuxLinux	Affected =6.10	Fixed in–

AI-suggested

A fix for this vulnerability is available in Linux kernel version 6.10 and associated commits (b950e84acd072ac648ace4fea53c0b1212da4b2c, b8f46ca5cbd629ffb91489ad7f970b3837835b0a, 996cce0c422b66a0e8b1a99505f896b0669ee5b6, 4d3c07591534517c633945c8d8e6526f10e3fabc). Users and administrators should upgrade to these fixed versions to mitigate the issue. No additional mitigation steps are indicated by the vendor advisory.

Description

CVE-2026-97549 addresses a vulnerability in the Linux kernel's XFS filesystem related to under-reservation of blocks when repairing short-form (sf) directories. The flaw causes incorrect block reservation calculations during directory repair operations, potentially leading to filesystem shutdowns due to insufficient space reservation in transactions. The issue arises from incorrect assumptions about directory block sizes and has been fixed by adjusting the reservation logic to correctly account for the filesystem block count. The fix is included in specific Linux kernel commits.

Impact

The under-reservation of blocks during directory repair can cause the filesystem to shut down unexpectedly. This may lead to denial of service conditions affecting system stability and availability. There is no indication of remote code execution or data corruption beyond the filesystem shutdown impact. No known exploits in the wild have been reported.

Summary

This vulnerability in the Linux kernel's XFS filesystem involves under-reservation of blocks during the repair of short-form directories. The problem was triggered by an assertion failure caused by incorrect assignment of the total block count in the xfs_da_args structure, which did not correctly reflect the directory block size relative to the filesystem block size. This led to under-reserving space in transactions, which can cause filesystem shutdowns. The root cause was traced to incorrect assumptions in the code about the number of filesystem blocks required for directory and extended attribute conversions. The fix involves using the xfs_dabuf_nfsb helper to correctly compute the required block count and adjusting related functions to avoid under-reservation. The vulnerability was fixed in Linux kernel version 6.10 and related commits.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 14:18 UTC

Technical details

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