Linux Kernel up to 6.12.108/6.18.49/7.2.3 btrfs btrfs_recover_relocation denial of service

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k0.00+

Summaryinfo

A vulnerability identified as problematic has been detected in Linux Kernel up to 6.12.108/6.18.49/7.2.3. This affects the function btrfs_recover_relocation of the component btrfs. This manipulation causes denial of service. This vulnerability appears as CVE-2026-89645. The attack requires local access. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.12.108/6.18.49/7.2.3 and classified as problematic. Affected by this vulnerability is the function btrfs_recover_relocation of the component btrfs. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

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.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-89645 since 09/11/2026. The exploitation appears to be easy. Attacking locally is a requirement. Additional levels of successful authentication are necessary for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.12.109, 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd/8a64baeb5bbb706b83d2235c1e39f5b77183817f/4d43107e807bcd92621106b07f5011411c6341a8/6d8ba4572922e336f0b59a80751b018e1e135164 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.4
VulDB Temp Score: 4.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.109/6.18.50/7.2.4/7.3-rc1
Patch: 2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd/8a64baeb5bbb706b83d2235c1e39f5b77183817f/4d43107e807bcd92621106b07f5011411c6341a8/6d8ba4572922e336f0b59a80751b018e1e135164

Timelineinfo

09/11/2026 CVE reserved
09/12/2026 +1 days Advisory disclosed
09/12/2026 +0 days VulDB entry created
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89645 (🔒)
GCVE (CVE): GCVE-0-2026-89645
GCVE (VulDB): GCVE-100-402943

Entryinfo

Created: 09/12/2026 02:01
Changes: 09/12/2026 02:01 (59)
Complete: 🔍
Cache ID: 216::103

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