Linux: Use After Free
CVE-2025-39854 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 2cde98a02da958357fe240a6ba269b69d913b6ba, 923c267bdbb64f65bc1149d184efcf8b047d7d64, f6486338fde3f04ed0ec59fe67a69a208c32734f as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.15% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 2cde98a02da958357fe240a6ba269b69d913b6ba or 923c267bdbb64f65bc1149d184efcf8b047d7d64 or f6486338fde3f04ed0ec59fe67a69a208c32734f, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.46 or 6.16.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 82e71b226e0ef770d7bc143701c8b4960b4eb3d5 up to, but not including, 2cde98a02da958357fe240a6ba269b69d913b6ba; 82e71b226e0ef770d7bc143701c8b4960b4eb3d5 up to, but not including, 923c267bdbb64f65bc1149d184efcf8b047d7d64; 82e71b226e0ef770d7bc143701c8b4960b4eb3d5 up to, but not including, f6486338fde3f04ed0ec59fe67a69a208c32734f; 6.8 | 2cde98a02da958357fe240a6ba269b69d913b6ba, 923c267bdbb64f65bc1149d184efcf8b047d7d64, f6486338fde3f04ed0ec59fe67a69a208c32734f |
| Linux | Linux Kernel | 6.8 up to, but not including, 6.12.46; 6.13 up to, but not including, 6.16.6; 6.17 | 6.12.46, 6.16.6 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: ice: fix NULL access of tx->in_use in ice_ll_ts_intr Recent versions of the E810 firmware have support for an extra interrupt to handle report of the "low latency" Tx timestamps coming from the specialized low latency firmware interface. Instead of polling the registers, software can wait until the low latency interrupt is fired. This logic makes use of the Tx timestamp tracking structure, ice_ptp_tx, as it uses the same "ready" bitmap to track which Tx timestamps complete. Unfortunately, the ice_ll_ts_intr() function does not check if the tracker is initialized before its first access. This results in NULL dereference or use-after-free bugs similar to the issues fixed in the ice_ptp_ts_irq() function. Fix this by only checking the in_use bitmap (and other fields) if the tracker is marked as initialized. The reset flow will clear the init field under lock before it tears the tracker down, thus preventing any use-after-free or NULL access.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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