Linux: Use After Free
CVE-2024-26739 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 0117fe0a4615a7c8d30d6ebcbf87332fbe63e6fd, 9d3ef89b6a5e9f2e940de2cef3d543be0be8dec5, e873e8f7d03a2ee5b77fb1a305c782fed98e2754 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 0.28% 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 0117fe0a4615a7c8d30d6ebcbf87332fbe63e6fd or 9d3ef89b6a5e9f2e940de2cef3d543be0be8dec5 or e873e8f7d03a2ee5b77fb1a305c782fed98e2754 or 28cdbbd38a4413b8eff53399b3f872fd4e80db9d, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.238 or 5.15.182 or 6.1.136 or 6.6.19, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e5cf1baf92cb785b90390db1c624948e70c8b8bd up to, but not including, 0117fe0a4615a7c8d30d6ebcbf87332fbe63e6fd; e5cf1baf92cb785b90390db1c624948e70c8b8bd up to, but not including, 9d3ef89b6a5e9f2e940de2cef3d543be0be8dec5; e5cf1baf92cb785b90390db1c624948e70c8b8bd up to, but not including, e873e8f7d03a2ee5b77fb1a305c782fed98e2754; e5cf1baf92cb785b90390db1c624948e70c8b8bd up to, but not including, 28cdbbd38a4413b8eff53399b3f872fd4e80db9d; e5cf1baf92cb785b90390db1c624948e70c8b8bd up to, but not including, f4e294bbdca8ac8757db436fc82214f3882fc7e7; e5cf1baf92cb785b90390db1c624948e70c8b8bd up to, but not including, 166c2c8a6a4dc2e4ceba9e10cfe81c3e469e3210; 4.19 | 0117fe0a4615a7c8d30d6ebcbf87332fbe63e6fd, 9d3ef89b6a5e9f2e940de2cef3d543be0be8dec5, e873e8f7d03a2ee5b77fb1a305c782fed98e2754, 28cdbbd38a4413b8eff53399b3f872fd4e80db9d, f4e294bbdca8ac8757db436fc82214f3882fc7e7, 166c2c8a6a4dc2e4ceba9e10cfe81c3e469e3210 |
| Debian | Debian Linux | 11.0 | Not stated |
| Linux | Linux Kernel | 4.19 up to, but not including, 5.10.238; 5.11 up to, but not including, 5.15.182; 5.16 up to, but not including, 6.1.136; 6.2 up to, but not including, 6.6.19; 6.7 up to, but not including, 6.7.7; 6.8 | 5.10.238, 5.15.182, 6.1.136, 6.6.19, 6.7.7 |
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 | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mirred: don't override retval if we already lost the skb If we're redirecting the skb, and haven't called tcf_mirred_forward(), yet, we need to tell the core to drop the skb by setting the retcode to SHOT. If we have called tcf_mirred_forward(), however, the skb is out of our hands and returning SHOT will lead to UaF. Move the retval override to the error path which actually need it.
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
- git.kernel.org/stable/c/0117fe0a4615a7c8d30d6ebcbf87332fbe63e6fd
- git.kernel.org/stable/c/166c2c8a6a4dc2e4ceba9e10cfe81c3e469e3210
- git.kernel.org/stable/c/28cdbbd38a4413b8eff53399b3f872fd4e80db9d
- git.kernel.org/stable/c/9d3ef89b6a5e9f2e940de2cef3d543be0be8dec5
- git.kernel.org/stable/c/e873e8f7d03a2ee5b77fb1a305c782fed98e2754
- git.kernel.org/stable/c/f4e294bbdca8ac8757db436fc82214f3882fc7e7
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2025/05/msg00045.htmlMailing List, Third Party Advisory
- lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlMailing List, Third Party Advisory
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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