Local privilege escalation via dangling AX.25 device pointer
Published Feb 27, 2025 · Updated Aug 5, 2026
Use-after-free in the Linux kernel AX.25 networking subsystem allows local users to disclose kernel memory or gain privileges. SO_BINDTODEVICE stores ax25->ax25_dev without taking a reference, and ax25_release() frees the object while dev->ax25_ptr still publishes it. An unprivileged local user in the initial namespace can re-dereference the dangling pointer through AF_AX25 socket syscalls, enabling heap disclosure, controlled writes, a kernel panic, or a networking deadlock.
Summary
What happened
Use-after-free in the Linux kernel AX.25 networking subsystem allows local users to disclose kernel memory or gain privileges. SO_BINDTODEVICE stores ax25->ax25_dev without taking a reference, and ax25_release() frees the object while dev->ax25_ptr still publishes it. An unprivileged local user in the initial namespace can re-dereference the dangling pointer through AF_AX25 socket syscalls, enabling heap disclosure, controlled writes, a kernel panic, or a networking deadlock.
The record
- CVE
- CVE-2025-21812
- Published
- Feb 27, 2025
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1068
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Feb 27, 2025CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=26a5adc8eb26d170058645c3cccd4d19165bec16
- Affected versionversion=3.18.132 <3.19
- Affected versionversion=3e881d8764ed9b04ae3e5c3e5d132acb75ef91ba
- Affected versionversion=4.14.92 <4.15
- Affected versionversion=4.19.14 <4.20
- Affected versionversion=4.20.1 <4.21
- Affected versionversion=4.4.170 <4.5
- Affected versionversion=4.9.149 <4.10
- Affected versionversion=5.0
- Affected versionversion=77768c96dcf860c43b970b87b2a09229f84ea560
- Affected versionversion=7f93d703e276311dd289c9a520ce9e8c8fa2858c
- Affected versionversion=c0e93a6d36135d5082cb3af8352f5b69c9f58d6e
- Affected versionversion=c39b8fd4997bf99503b8e48d8cb0eedb1d9a54f0
- Affected versionversion=c433570458e49bccea5c551df628d058b3526289 <2802ed4ced27ebd474828fc67ffd7d66f11e3605
- Affected versionversion=c433570458e49bccea5c551df628d058b3526289 <7705d8a7f2c26c80973c81093db07c6022b2b30e
- Affected versionversion=c433570458e49bccea5c551df628d058b3526289 <8937f5e38a218531dce2a89fae60e3adcc2311e1
- Affected versionversion=c433570458e49bccea5c551df628d058b3526289 <95fc45d1dea8e1253f8ec58abc5befb71553d666
- Affected versionversion=c433570458e49bccea5c551df628d058b3526289 <c2531db6de3c95551be58878f859c6a053b7eb2e
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What is affected?
Published CVSS scores
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Attacks
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