VulnerabilityPublished 11 Sep 2026Updated 21 Oct 2026

CVE-2026-89645: Linux kernel · btrfs: drop recovered reloc root refs on recovery failure

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd, 8a64baeb5bbb706b83d2235c1e39f5b77183817f, 7b8c6af17287899a5d00c70566831feac237d192 +2

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

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ f44deb7442edf42abee6be25fca7e3e86061b4c9, < 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd	Fixed in 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd
LinuxLinux	Affected ≥ f44deb7442edf42abee6be25fca7e3e86061b4c9, < 8a64baeb5bbb706b83d2235c1e39f5b77183817f	Fixed in 8a64baeb5bbb706b83d2235c1e39f5b77183817f
LinuxLinux	Affected ≥ f44deb7442edf42abee6be25fca7e3e86061b4c9, < 7b8c6af17287899a5d00c70566831feac237d192	Fixed in 7b8c6af17287899a5d00c70566831feac237d192
LinuxLinux	Affected ≥ f44deb7442edf42abee6be25fca7e3e86061b4c9, < 6d8ba4572922e336f0b59a80751b018e1e135164	Fixed in 6d8ba4572922e336f0b59a80751b018e1e135164
LinuxLinux	Affected ≥ f44deb7442edf42abee6be25fca7e3e86061b4c9, < 4d43107e807bcd92621106b07f5011411c6341a8	Fixed in 4d43107e807bcd92621106b07f5011411c6341a8
LinuxLinux	Affected =5.7	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: drop recovered reloc root refs on recovery failure During relocation recovery, each fs root gets a reference to its relocation root. If loading or adding a later root fails, or if the first transaction commit fails, btrfs_recover_relocation() jumps to out_unset before merge_reloc_roots() and clean_dirty_subvols(). put_reloc_control() drops the list-owned relocation root references, but it does not clear fs_root->reloc_root or drop the references owned by those pointers. Mount cleanup only drops them when BTRFS_FS_ERROR is set, so an error such as -ENOMEM while processing a later root can leave references behind. Keep temporary references to the fs roots associated during recovery. On failure, clear their reloc_root pointers and drop the corresponding references. Once the first transaction commit succeeds, drop only the temporary fs root references and let the normal merge and cleanup paths handle the relocation roots. Fault injection on a pending-relocation image confirmed the cleanup gap. With an injected first-commit failure, 25 fs roots had reloc_root set with fs_error=0. With this fix, the same failure path drops that count to 0 before mount fails.

References

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