Linux: Use After Free
CVE-2026-53161 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 c6e5c2be09f814377d7f1ce97370a5b7b3e02814, e1e3a05efe5954d5bad01157d79429d39a67a7ae, d42679eef34dd590b694ce3b666c5e2ba10cd4bf 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 0.13% 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 c6e5c2be09f814377d7f1ce97370a5b7b3e02814 or e1e3a05efe5954d5bad01157d79429d39a67a7ae or d42679eef34dd590b694ce3b666c5e2ba10cd4bf or df08fadcf0e5f3708365ec3b6d30b5aafd98bea1, 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 | 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, c6e5c2be09f814377d7f1ce97370a5b7b3e02814; 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, e1e3a05efe5954d5bad01157d79429d39a67a7ae; 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, d42679eef34dd590b694ce3b666c5e2ba10cd4bf; 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, df08fadcf0e5f3708365ec3b6d30b5aafd98bea1; 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, ecea4967c2bff92c2fafbc59893f711b39f7b152; 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, 5278ccd357e0d7aeeb1e76c0f3e0e02894a9897c; 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, fbe0947420eec18a84638d29468c2d563ce4e6a3; 6cffd79504ce040f460831030d3069fa1c99bb71 up to, but not including, e85eb5feca8e254905ffa6c57a3c99c89a674a0f; and 1 more ranges | c6e5c2be09f814377d7f1ce97370a5b7b3e02814, e1e3a05efe5954d5bad01157d79429d39a67a7ae, d42679eef34dd590b694ce3b666c5e2ba10cd4bf, df08fadcf0e5f3708365ec3b6d30b5aafd98bea1, ecea4967c2bff92c2fafbc59893f711b39f7b152, 5278ccd357e0d7aeeb1e76c0f3e0e02894a9897c |
| Linux | Linux Kernel | 5.1 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: misc: fastrpc: fix use-after-free of fastrpc_user in workqueue context There is a race between fastrpc_device_release() and the workqueue that processes DSP responses. When the user closes the file descriptor, fastrpc_device_release() frees the fastrpc_user structure. Concurrently, an in-flight DSP invocation can complete and fastrpc_rpmsg_callback() schedules context cleanup via schedule_work(&ctx->put_work). If the workqueue runs fastrpc_context_free() in parallel with or after fastrpc_device_release() has freed the user structure, it dereferences the freed fastrpc_user. Depending on the state of the context at the time of the race, any one of the following accesses can be hit: 1. fastrpc_buf_free() calls fastrpc_ipa_to_dma_addr(buf->fl->cctx, ...) to strip the SID bits from the stored IOVA before passing the physical address to dma_free_coherent(). 2. fastrpc_free_map() reads map->fl->cctx->vmperms[0].vmid to reconstruct the source permission bitmask needed for the qcom_scm_assign_mem() call that returns memory from the DSP VM back to HLOS. 3. fastrpc_free_map() acquires map->fl->lock to safely remove the map node from the fl->maps list. The resulting use-after-free manifests as: pc : fastrpc_buf_free+0x38/0x80 [fastrpc] lr : fastrpc_context_free+0xa8/0x1b0 [fastrpc] fastrpc_context_free+0xa8/0x1b0 [fastrpc] fastrpc_context_put_wq+0x78/0xa0 [fastrpc] process_one_work+0x180/0x450 worker_thread+0x26c/0x388 Add kref-based reference counting to fastrpc_user. Have each invoke context take a reference on the user at allocation time and release it when the context is freed. Release the initial reference in fastrpc_device_release() at file close. Move the teardown of the user structure — freeing pending contexts, maps, mmaps, and the channel context reference — into the kref release callback fastrpc_user_free(), so that it runs only when the last reference is dropped, regardless of whether that happens at device close or after the final in-flight context completes.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/5278ccd357e0d7aeeb1e76c0f3e0e02894a9897c
- git.kernel.org/stable/c/c6e5c2be09f814377d7f1ce97370a5b7b3e02814
- git.kernel.org/stable/c/d42679eef34dd590b694ce3b666c5e2ba10cd4bf
- git.kernel.org/stable/c/df08fadcf0e5f3708365ec3b6d30b5aafd98bea1
- git.kernel.org/stable/c/e1e3a05efe5954d5bad01157d79429d39a67a7ae
- git.kernel.org/stable/c/e85eb5feca8e254905ffa6c57a3c99c89a674a0f
- git.kernel.org/stable/c/ecea4967c2bff92c2fafbc59893f711b39f7b152
- git.kernel.org/stable/c/fbe0947420eec18a84638d29468c2d563ce4e6a3
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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