Linux: Use After Free
CVE-2026-43339 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 eec49a33611f20336b357b3953df44f1a02049e8, bacc7f31085c9820922f00bc7d79756ffa13123a, 7bfafa1b0cd582983ebec6bb20f0a435528fe567 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 0.16% 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 eec49a33611f20336b357b3953df44f1a02049e8 or bacc7f31085c9820922f00bc7d79756ffa13123a or 7bfafa1b0cd582983ebec6bb20f0a435528fe567 or 7d9f2f4aabd116ca68fbdab5d8fb8dac74c2ea1e, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.168 or 6.6.134, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, eec49a33611f20336b357b3953df44f1a02049e8; f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, bacc7f31085c9820922f00bc7d79756ffa13123a; f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, 7bfafa1b0cd582983ebec6bb20f0a435528fe567; f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, 7d9f2f4aabd116ca68fbdab5d8fb8dac74c2ea1e; f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, 25357b670afb5b517096da783abaa5cc4bf8359e; f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, 3cd4efb5df72843dfac892d0b3c7a4a8bd926b65; f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, 2d88ed7fa000e19c2dc0fa31b3a849e3f5bca5c1; f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac up to, but not including, fd63f185979b047fb22a0dfc6bd94d0cab6a6a70; and 1 more ranges | eec49a33611f20336b357b3953df44f1a02049e8, bacc7f31085c9820922f00bc7d79756ffa13123a, 7bfafa1b0cd582983ebec6bb20f0a435528fe567, 7d9f2f4aabd116ca68fbdab5d8fb8dac74c2ea1e, 25357b670afb5b517096da783abaa5cc4bf8359e, 3cd4efb5df72843dfac892d0b3c7a4a8bd926b65 |
| Linux | Linux Kernel | 4.6 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.134; 6.7 up to, but not including, 6.12.81; 6.13 up to, but not including, 6.18.22; 6.19 up to, but not including, 6.19.12; 7.0 | 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.22 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: ipv6: prevent possible UaF in addrconf_permanent_addr() The mentioned helper try to warn the user about an exceptional condition, but the message is delivered too late, accessing the ipv6 after its possible deletion. Reorder the statement to avoid the possible UaF; while at it, place the warning outside the idev->lock as it needs no protection.
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/25357b670afb5b517096da783abaa5cc4bf8359e
- git.kernel.org/stable/c/2d88ed7fa000e19c2dc0fa31b3a849e3f5bca5c1
- git.kernel.org/stable/c/3cd4efb5df72843dfac892d0b3c7a4a8bd926b65
- git.kernel.org/stable/c/7bfafa1b0cd582983ebec6bb20f0a435528fe567
- git.kernel.org/stable/c/7d9f2f4aabd116ca68fbdab5d8fb8dac74c2ea1e
- git.kernel.org/stable/c/bacc7f31085c9820922f00bc7d79756ffa13123a
- git.kernel.org/stable/c/eec49a33611f20336b357b3953df44f1a02049e8
- git.kernel.org/stable/c/fd63f185979b047fb22a0dfc6bd94d0cab6a6a70
Recent Use After Free vulnerabilities
- 7.3 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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