Linux: Use After Free
CVE-2026-31474 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 cb3d6efa78460e6d50bf68806d0db66265709f64, 9649d051e54413049c009638ec1dc23962c884a4, eec8a1b18a79600bd4419079dc0026c1db72a830 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 0.1% 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 cb3d6efa78460e6d50bf68806d0db66265709f64 or 9649d051e54413049c009638ec1dc23962c884a4 or eec8a1b18a79600bd4419079dc0026c1db72a830 or 2e62e7051eca75a7f2e3d52d62ec10d7d7aa358c, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.131 or 6.12.80 or 6.18.21 or 6.19.11, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 96d1c81e6a0478535342dff6c730adb076cd84e8 up to, but not including, cb3d6efa78460e6d50bf68806d0db66265709f64; 96d1c81e6a0478535342dff6c730adb076cd84e8 up to, but not including, 9649d051e54413049c009638ec1dc23962c884a4; 96d1c81e6a0478535342dff6c730adb076cd84e8 up to, but not including, eec8a1b18a79600bd4419079dc0026c1db72a830; 96d1c81e6a0478535342dff6c730adb076cd84e8 up to, but not including, 2e62e7051eca75a7f2e3d52d62ec10d7d7aa358c; 96d1c81e6a0478535342dff6c730adb076cd84e8 up to, but not including, 424e95d62110cdbc8fd12b40918f37e408e35a92; 6.4 | cb3d6efa78460e6d50bf68806d0db66265709f64, 9649d051e54413049c009638ec1dc23962c884a4, eec8a1b18a79600bd4419079dc0026c1db72a830, 2e62e7051eca75a7f2e3d52d62ec10d7d7aa358c, 424e95d62110cdbc8fd12b40918f37e408e35a92 |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Linux | Linux Kernel | 6.4.1 up to, but not including, 6.6.131; 6.7 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 6.4; 7.0 | 6.6.131, 6.12.80, 6.18.21, 6.19.11 |
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 CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: can: isotp: fix tx.buf use-after-free in isotp_sendmsg() isotp_sendmsg() uses only cmpxchg() on so->tx.state to serialize access to so->tx.buf. isotp_release() waits for ISOTP_IDLE via wait_event_interruptible() and then calls kfree(so->tx.buf). If a signal interrupts the wait_event_interruptible() inside close() while tx.state is ISOTP_SENDING, the loop exits early and release proceeds to force ISOTP_SHUTDOWN and continues to kfree(so->tx.buf) while sendmsg may still be reading so->tx.buf for the final CAN frame in isotp_fill_dataframe(). The so->tx.buf can be allocated once when the standard tx.buf length needs to be extended. Move the kfree() of this potentially extended tx.buf to sk_destruct time when either isotp_sendmsg() and isotp_release() are done.
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
- git.kernel.org/stable/c/2e62e7051eca75a7f2e3d52d62ec10d7d7aa358c
- git.kernel.org/stable/c/424e95d62110cdbc8fd12b40918f37e408e35a92
- git.kernel.org/stable/c/9649d051e54413049c009638ec1dc23962c884a4
- git.kernel.org/stable/c/cb3d6efa78460e6d50bf68806d0db66265709f64
- git.kernel.org/stable/c/eec8a1b18a79600bd4419079dc0026c1db72a830
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
Spotted an error? Tell us.