Linux Kernel up to 6.18.44/7.1.8 x25 net/x25 x25_heartbeat_expiry use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k1.29-

Summaryinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel up to 6.18.44/7.1.8. This issue affects the function x25_heartbeat_expiry of the file net/x25 of the component x25. The manipulation leads to use after free. This vulnerability is traded as CVE-2026-74628. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel up to 6.18.44/7.1.8. This issue affects the function x25_heartbeat_expiry of the file net/x25 of the component x25. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free of the socket by its timers The x25 timers are armed with mod_timer() and cancelled with timer_delete(), so a pending timer holds no reference on the socket and a cancel does not wait for a callback already running on another CPU. x25_heartbeat_expiry() also rearms unconditionally, so it can reinstall sk->sk_timer after __x25_destroy_socket() has passed its cancel point. The following __sock_put() frees the socket while the timer is still queued, and the next expiry uses freed memory. KASAN reports a slab-use-after-free on the kmalloc-2k object freed by close(). timer_delete_sync() cannot be used here: x25_heartbeat_expiry() and x25_timer_expiry() both reach the cancels from inside the timer they would wait on, through __x25_destroy_socket() and x25_disconnect(). Arm the timers with sk_reset_timer() and cancel them with sk_stop_timer() so that an armed timer owns a reference, and release it in both expiry handlers. Rearm the heartbeat only while sk_hashed(sk) is still true, since __x25_destroy_socket() unlinks the socket before dropping it. Arm the deferred destroy timer the same way and drop its reference in x25_destroy_timer(). Reproduced on net with KASAN, with the heartbeat period shortened so the window recurs. With this patch the reproducer no longer triggers a report and /proc/net/x25 drains. Discovered by XBOW, triaged by Baul Lee <[email protected]>

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-74628 since 08/15/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/22/2026).

Upgrading to version 6.18.45 or 7.1.9 eliminates this vulnerability. Applying the patch 4bc522b33438fefc3272840ae5988771863a4f1f/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda/2195424c3da2ef1829a63b807e3a900a90e57d85 is able to eliminate this problem.

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Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
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: No
Local: No
Remote: Yes

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 6.18.45/7.1.9
Patch: 4bc522b33438fefc3272840ae5988771863a4f1f/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda/2195424c3da2ef1829a63b807e3a900a90e57d85

Timelineinfo

08/15/2026 CVE reserved
08/22/2026 +7 days Advisory disclosed
08/22/2026 +0 days VulDB entry created
08/22/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74628 (🔒)
GCVE (CVE): GCVE-0-2026-74628
GCVE (VulDB): GCVE-100-394409

Entryinfo

Created: 08/22/2026 18:24
Changes: 08/22/2026 18:24 (60)
Complete: 🔍
Cache ID: 216::103

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