Linux Kernel up to 6.18.39/7.1.4 alloc_tag /proc/allocinfo allocinfo_start use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.8$0-$5k1.45

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.39/7.1.4. It has been declared as very critical. This issue affects the function allocinfo_start of the file /proc/allocinfo of the component alloc_tag. Executing a manipulation can lead to use after free. The identification of this vulnerability is CVE-2026-72431. The attack can only be executed locally. There is no exploit available.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.18.39/7.1.4 and classified as very critical. This vulnerability affects the function allocinfo_start of the file /proc/allocinfo of the component alloc_tag. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: alloc_tag: fix use-after-free in /proc/allocinfo after module unload allocinfo_start() only reinitializes the codetag iterator at position 0. For subsequent reads (position > 0), it reuses cached iterator state from the previous batch. allocinfo_stop() drops mod_lock between read batches, which allows module unload to complete and free the module memory that the cached iterator still references: CPU0 (read) CPU1 (rmmod) ---- ---- allocinfo_start(pos=0) down_read(mod_lock) allocinfo_show() ... allocinfo_stop() up_read(mod_lock) codetag_unload_module() kfree(cmod) release_module_tags() ... free_mod_mem() allocinfo_start(pos=N) down_read(mod_lock) // reuses cached iter, skips re-init allocinfo_show() ct->filename <-- UAF After free_mod_mem() frees the module's .rodata, allocinfo_show() dereferences ct->filename, ct->function which point there. Save the iterator state in allocinfo_next() and resume from it in allocinfo_start() with codetag_next_ct(), which detects module removal via idr_find() returning NULL and skips to the next module.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-72431 since 08/09/2026. The exploitation appears to be easy. Local access is required to approach this attack. Additional levels of successful authentication are needed for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/15/2026).

Upgrading to version 6.18.40, 7.1.5 or 7.2-rc1 eliminates this vulnerability. Applying the patch 37e3e8a2c3bfdd503209f043f8bbfbdcf5a1d92f/008ceffd44040f809aead6d7bef7cb1210c4149a/2956268efc457cb05d29c1bf94de1e8e684d7bbc is able to eliminate this problem.

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Productinfo

Type

Vendor

Name

Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.2
VulDB Meta Temp Score: 7.8

VulDB Base Score: 8.2
VulDB Temp Score: 7.8
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: Use after free
CWE: CWE-416 / CWE-119
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 6.18.40/7.1.5/7.2-rc1
Patch: 37e3e8a2c3bfdd503209f043f8bbfbdcf5a1d92f/008ceffd44040f809aead6d7bef7cb1210c4149a/2956268efc457cb05d29c1bf94de1e8e684d7bbc

Timelineinfo

08/09/2026 CVE reserved
08/15/2026 +6 days Advisory disclosed
08/15/2026 +0 days VulDB entry created
08/15/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-72431 (🔒)
GCVE (CVE): GCVE-0-2026-72431
GCVE (VulDB): GCVE-100-391054

Entryinfo

Created: 08/15/2026 17:19
Changes: 08/15/2026 17:19 (60)
Complete: 🔍
Cache ID: 216::103

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