Linux: Use After Free
CVE-2024-26800 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 f2b85a4cc763841843de693bbd7308fe9a2c4c89, 81be85353b0f5a7b660635634b655329b429eefe, 1ac9fb84bc7ecd4bc6428118301d9d864d2a58d1 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 0.74% chance of exploitation within 30 days, higher than 55% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to f2b85a4cc763841843de693bbd7308fe9a2c4c89 or 81be85353b0f5a7b660635634b655329b429eefe or 1ac9fb84bc7ecd4bc6428118301d9d864d2a58d1 or 13114dc5543069f7b97991e3b79937b6da05f5b0, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.16 or 6.6.21 or 6.7.9, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | cd1bbca03f3c1d845ce274c0d0a66de8e5929f72 up to, but not including, f2b85a4cc763841843de693bbd7308fe9a2c4c89; 13eca403876bbea3716e82cdfe6f1e6febb38754 up to, but not including, 81be85353b0f5a7b660635634b655329b429eefe; ab6397f072e5097f267abf5cb08a8004e6b17694 up to, but not including, 1ac9fb84bc7ecd4bc6428118301d9d864d2a58d1; 8590541473188741055d27b955db0777569438e3 up to, but not including, 13114dc5543069f7b97991e3b79937b6da05f5b0; 3ade391adc584f17b5570fd205de3ad029090368; 5.15.160 up to, but not including, 5.16; 6.6.18 up to, but not including, 6.6.21; 6.7.6 up to, but not including, 6.7.9 | f2b85a4cc763841843de693bbd7308fe9a2c4c89, 81be85353b0f5a7b660635634b655329b429eefe, 1ac9fb84bc7ecd4bc6428118301d9d864d2a58d1, 13114dc5543069f7b97991e3b79937b6da05f5b0, 5.16, 6.6.21 |
| Linux | Linux Kernel | 5.15.160 up to, but not including, 5.16; 6.6.18 up to, but not including, 6.6.21; 6.7.6 up to, but not including, 6.7.9; 6.8 | 5.16, 6.6.21, 6.7.9 |
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 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: tls: fix use-after-free on failed backlog decryption When the decrypt request goes to the backlog and crypto_aead_decrypt returns -EBUSY, tls_do_decryption will wait until all async decryptions have completed. If one of them fails, tls_do_decryption will return -EBADMSG and tls_decrypt_sg jumps to the error path, releasing all the pages. But the pages have been passed to the async callback, and have already been released by tls_decrypt_done. The only true async case is when crypto_aead_decrypt returns -EINPROGRESS. With -EBUSY, we already waited so we can tell tls_sw_recvmsg that the data is available for immediate copy, but we need to notify tls_decrypt_sg (via the new ->async_done flag) that the memory has already been released.
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: partial).
- 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
Spotted an error? Tell us.