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NVD / CVE Program· CNA Linux

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

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: 0.22% (FIRST EPSS).
  • Fixed version: Linux Linux 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd, 4d43107e807bcd92621106b07f5011411c6341a8, 6d8ba4572922e336f0b59a80751b018e1e135164; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd, 4d43107e807bcd92621106b07f5011411c6341a8, 6d8ba4572922e336f0b59a80751b018e1e135164; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes 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: 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.

—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 21, 2026
EPSS
0.2% · 13th 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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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

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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

    • 5.7affected
    • f44deb7442edf42abee6be25fca7e3e86061b4c9 and later · before 7b8c6af17287899a5d00c70566831feac237d192affected · git
    • f44deb7442edf42abee6be25fca7e3e86061b4c9 and later · before 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fdaffected · git
    • f44deb7442edf42abee6be25fca7e3e86061b4c9 and later · before 8a64baeb5bbb706b83d2235c1e39f5b77183817faffected · git
    • f44deb7442edf42abee6be25fca7e3e86061b4c9 and later · before 4d43107e807bcd92621106b07f5011411c6341a8affected · git
    • f44deb7442edf42abee6be25fca7e3e86061b4c9 and later · before 6d8ba4572922e336f0b59a80751b018e1e135164affected · git
    • before 5.7not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver
    • 6.12.109 and later · up to and including 6.12.*not affected · semver
    • 6.18.50 and later · up to and including 6.18.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
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-2026-89643Sep 11, 2026 · audit: avoid dropping live tree ref on fsnotify rule autoremove
    39Monitor
  • ← EarlierCVE-2026-89644Sep 11, 2026 · btrfs: fix extent map leak in NOCOW direct I/O write
    0Monitor
  • Later →CVE-2026-89646Sep 11, 2026 · ceph: fix leaked inode reference on writeback abort at umount
    31Monitor

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 Linux2256d6dc5b88841a8a8b4fd9a9f04730705fb6fdVendor (CNA)
Linux Linux4d43107e807bcd92621106b07f5011411c6341a8Vendor (CNA)
Linux Linux6d8ba4572922e336f0b59a80751b018e1e135164Vendor (CNA)
Linux Linux7b8c6af17287899a5d00c70566831feac237d192Vendor (CNA)
Linux Linux8a64baeb5bbb706b83d2235c1e39f5b77183817fVendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
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✗ → ✓

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References

Show all references (4 more)

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

All records