Linux: Double Free
CVE-2026-43494 is a high-severity double 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 c6e51512a784c4a7b86e1a044988696e3b3721fa, 03014551938a0887fa55f18ce49b70158a9c0113, d84ce1786ce40fdd3dd98db47aec5527817e1ef6 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 0.41% 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 c6e51512a784c4a7b86e1a044988696e3b3721fa or 03014551938a0887fa55f18ce49b70158a9c0113 or d84ce1786ce40fdd3dd98db47aec5527817e1ef6 or 9115669faedccdda100428e2d26fd0aac8c50799, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.258 or 5.15.209 or 6.1.175 or 6.6.141, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, c6e51512a784c4a7b86e1a044988696e3b3721fa; 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, 03014551938a0887fa55f18ce49b70158a9c0113; 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, d84ce1786ce40fdd3dd98db47aec5527817e1ef6; 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, 9115669faedccdda100428e2d26fd0aac8c50799; 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, 0bbbff00a15b1df2cac9014d6cf4b6890f473353; 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, 640e37f58f991546a87540d067279c2c1fa9fe51; 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, 290e833d1acb1093bc121fcdc97f5e6161157479; 0cebaccef3acbdfbc2d85880a2efb765d2f4e2e3 up to, but not including, e174929793195e0cd6a4adb0cad731b39f9019b4; and 1 more ranges | c6e51512a784c4a7b86e1a044988696e3b3721fa, 03014551938a0887fa55f18ce49b70158a9c0113, d84ce1786ce40fdd3dd98db47aec5527817e1ef6, 9115669faedccdda100428e2d26fd0aac8c50799, 0bbbff00a15b1df2cac9014d6cf4b6890f473353, 640e37f58f991546a87540d067279c2c1fa9fe51 |
| Red Hat | Red Hat Enterprise Linux 10 | 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 |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Linux | Linux Kernel | 4.17 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.141; 6.7 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10; 7.1 | 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33 |
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 | 7.0 | High | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: net/rds: reset op_nents when zerocopy page pin fails When iov_iter_get_pages2() fails in rds_message_zcopy_from_user(), the pinned pages are released with put_page(), and rm->data.op_mmp_znotifier is cleared. But we fail to properly clear rm->data.op_nents. Later when rds_message_purge() is called from rds_sendmsg() the cleanup loop iterates over the incorrectly non zero number of op_nents and frees them again. Fix this by properly resetting op_nents when it should be in rds_message_zcopy_from_user().
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
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/03014551938a0887fa55f18ce49b70158a9c0113
- git.kernel.org/stable/c/0bbbff00a15b1df2cac9014d6cf4b6890f473353
- git.kernel.org/stable/c/290e833d1acb1093bc121fcdc97f5e6161157479
- git.kernel.org/stable/c/640e37f58f991546a87540d067279c2c1fa9fe51
- git.kernel.org/stable/c/9115669faedccdda100428e2d26fd0aac8c50799
- git.kernel.org/stable/c/c6e51512a784c4a7b86e1a044988696e3b3721fa
- git.kernel.org/stable/c/d84ce1786ce40fdd3dd98db47aec5527817e1ef6
- git.kernel.org/stable/c/e174929793195e0cd6a4adb0cad731b39f9019b4
Technical write-ups (may include proof of concept)
- github.com/v12-security/pocs/tree/main/pintheftExploit, Third Party Advisory
Other references
Recent Double Free vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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