Linux: Use After Free
CVE-2026-53212 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 349df61526d2e39decc685d246202e3e284cfe05, 55b79b1ae42372012413ce0413181d26679b17ef, 5e9ee18b27fde88cb6148202b33916c66693fe82 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 0.19% 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 349df61526d2e39decc685d246202e3e284cfe05 or 55b79b1ae42372012413ce0413181d26679b17ef or 5e9ee18b27fde88cb6148202b33916c66693fe82 or 8767fe4079affa74314d7eb3220e700150289842, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, 349df61526d2e39decc685d246202e3e284cfe05; af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, 55b79b1ae42372012413ce0413181d26679b17ef; af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, 5e9ee18b27fde88cb6148202b33916c66693fe82; af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, 8767fe4079affa74314d7eb3220e700150289842; af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, fda6573a46ad24f35348e024905ee5bdf729797e; af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, 941d7394efda5e054e2d6f3e0dd0f6a9ba19aaa3; af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, f9a0e4b61054cde89a2a77845293c726cc07cc43; af308b94a2a4a5a27bec9028354c4df444a7c8ba up to, but not including, c32b26aaa2f9216520a38b3f4bfeec846eb3eb8a; and 1 more ranges | 349df61526d2e39decc685d246202e3e284cfe05, 55b79b1ae42372012413ce0413181d26679b17ef, 5e9ee18b27fde88cb6148202b33916c66693fe82, 8767fe4079affa74314d7eb3220e700150289842, fda6573a46ad24f35348e024905ee5bdf729797e, 941d7394efda5e054e2d6f3e0dd0f6a9ba19aaa3 |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Linux | Linux Kernel | 4.19 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.94; 6.13 up to, but not including, 6.18.36; 6.19 up to, but not including, 7.0.13; 7.1 | 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36 |
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: netfilter: nft_tunnel: fix use-after-free on object destroy nft_tunnel_obj_destroy() calls metadata_dst_free() which directly kfree()s the metadata_dst, ignoring the dst_entry refcount. Packets that took a reference via dst_hold() in nft_tunnel_obj_eval() and are still queued (e.g. in a netem qdisc) are left with a dangling pointer. When these packets are eventually dequeued, dst_release() operates on freed memory. Replace metadata_dst_free() with dst_release() so the metadata_dst is freed only after all references are dropped. The dst subsystem already handles metadata_dst cleanup in dst_destroy() when DST_METADATA is set.
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/349df61526d2e39decc685d246202e3e284cfe05
- git.kernel.org/stable/c/55b79b1ae42372012413ce0413181d26679b17ef
- git.kernel.org/stable/c/5e9ee18b27fde88cb6148202b33916c66693fe82
- git.kernel.org/stable/c/8767fe4079affa74314d7eb3220e700150289842
- git.kernel.org/stable/c/941d7394efda5e054e2d6f3e0dd0f6a9ba19aaa3
- git.kernel.org/stable/c/c32b26aaa2f9216520a38b3f4bfeec846eb3eb8a
- git.kernel.org/stable/c/f9a0e4b61054cde89a2a77845293c726cc07cc43
- git.kernel.org/stable/c/fda6573a46ad24f35348e024905ee5bdf729797e
Other references
Recent Use After Free vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 8.2 High severity
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