Linux Kernel up to 6.19.5 _leaf_add allocation of resources

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5.3$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.19.5. It has been classified as critical. Affected by this issue is the function _leaf_add. The manipulation leads to allocation of resources. This vulnerability is listed as CVE-2026-43187. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.5 and classified as critical. This issue affects the function _leaf_add. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 ("xfs: fix attr leaf header freemap.size underflow"), Brian Foster observed that it's possible for a small freemap at the end of the end of the xattr entries array to experience a size underflow when subtracting the space consumed by an expansion of the entries array. There are only three freemap entries, which means that it is not a complete index of all free space in the leaf block. This code can leave behind a zero-length freemap entry with a nonzero base. Subsequent setxattr operations can increase the base up to the point that it overlaps with another freemap entry. This isn't in and of itself a problem because the code in _leaf_add that finds free space ignores any freemap entry with zero size. However, there's another bug in the freemap update code in _leaf_add, which is that it fails to update a freemap entry that begins midway through the xattr entry that was just appended to the array. That can result in the freemap containing two entries with the same base but different sizes (0 for the "pushed-up" entry, nonzero for the entry that's actually tracking free space). A subsequent _leaf_add can then allocate xattr namevalue entries on top of the entries array, leading to data loss. But fixing that is for later. For now, eliminate the possibility of confusion by zeroing out the base of any freemap entry that has zero size. Because the freemap is not intended to be a complete index of free space, a subsequent failure to find any free space for a new xattr will trigger block compaction, which regenerates the freemap. It looks like this bug has been in the codebase for quite a long time.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-43187 since 05/01/2026. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 318589 (Oracle Linux 10 / 9 : Unbreakable Enterprise kernel (ELSA-2026-50293)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16 or 6.19.6 eliminates this vulnerability. Applying the patch f3c0d1fc1eadbb4adbee5ab7757d41d35f48325b/aa9083d97e2157da3c6fb45ddb1a97af7f188f7f/a631899025d47ea1aa6464d76db5b4d3b6d196fd/ffaf5c99d0f862db021fb1af8b813c1416b1beb2/e1b8c6452ee99a30e188a88f3f3f804fb1c6004a/f31a8334e1c54b126fcecf98645a49b6bc5ad399/479b05fc3ee272090f671b06a41f3da8aa78eece/6f13c1d2a6271c2e73226864a0e83de2770b6f34 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (318589). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
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: Allocation of resources
CWE: CWE-770 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 318589
Nessus Name: Oracle Linux 10 / 9 : Unbreakable Enterprise kernel (ELSA-2026-50293)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.252/5.15.202/6.1.165/6.6.128/6.12.75/6.18.16/6.19.6
Patch: f3c0d1fc1eadbb4adbee5ab7757d41d35f48325b/aa9083d97e2157da3c6fb45ddb1a97af7f188f7f/a631899025d47ea1aa6464d76db5b4d3b6d196fd/ffaf5c99d0f862db021fb1af8b813c1416b1beb2/e1b8c6452ee99a30e188a88f3f3f804fb1c6004a/f31a8334e1c54b126fcecf98645a49b6bc5ad399/479b05fc3ee272090f671b06a41f3da8aa78eece/6f13c1d2a6271c2e73226864a0e83de2770b6f34

Timelineinfo

05/01/2026 CVE reserved
05/06/2026 +5 days Advisory disclosed
05/06/2026 +0 days VulDB entry created
06/04/2026 +29 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-43187 (🔒)
GCVE (CVE): GCVE-0-2026-43187
GCVE (VulDB): GCVE-100-361373

Entryinfo

Created: 05/06/2026 16:25
Updated: 06/04/2026 18:55
Changes: 05/06/2026 16:25 (58), 06/04/2026 18:55 (2)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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