Linux: Use After Free
CVE-2026-22980 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 ca97360860eb02e3ae4ba42c19b439a0fcecbf06, e8bfa2401d4c51eca6e48e9b33c798828ca9df61, 34eb22836e0cdba093baac66599d68c4cd245a9d 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 0.15% 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 ca97360860eb02e3ae4ba42c19b439a0fcecbf06 or e8bfa2401d4c51eca6e48e9b33c798828ca9df61 or 34eb22836e0cdba093baac66599d68c4cd245a9d or 06600719d0f7a723811c45e4d51f5b742f345309, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.248 or 5.15.198 or 6.1.161 or 6.6.121, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 up to, but not including, ca97360860eb02e3ae4ba42c19b439a0fcecbf06; 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 up to, but not including, e8bfa2401d4c51eca6e48e9b33c798828ca9df61; 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 up to, but not including, 34eb22836e0cdba093baac66599d68c4cd245a9d; 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 up to, but not including, 06600719d0f7a723811c45e4d51f5b742f345309; 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 up to, but not including, ba4811c8b433bfa681729ca42cc62b6034f223b0; 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 up to, but not including, 53f07d095e7e680c5e4569a55a019f2c0348cdc6; 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 up to, but not including, 2857bd59feb63fcf40fe4baf55401baea6b4feb4; 3.18 | ca97360860eb02e3ae4ba42c19b439a0fcecbf06, e8bfa2401d4c51eca6e48e9b33c798828ca9df61, 34eb22836e0cdba093baac66599d68c4cd245a9d, 06600719d0f7a723811c45e4d51f5b742f345309, ba4811c8b433bfa681729ca42cc62b6034f223b0, 53f07d095e7e680c5e4569a55a019f2c0348cdc6 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 3.18 up to, but not including, 5.10.248; 5.11 up to, but not including, 5.15.198; 5.16 up to, but not including, 6.1.161; 6.2 up to, but not including, 6.6.121; 6.7 up to, but not including, 6.12.66; 6.13 up to, but not including, 6.18.6; 6.19 | 5.10.248, 5.15.198, 6.1.161, 6.6.121, 6.12.66, 6.18.6 |
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: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field "client_tracking_active" which is set as described. Another field "grace_end_forced", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This "grace_end_forced" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.
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/06600719d0f7a723811c45e4d51f5b742f345309
- git.kernel.org/stable/c/2857bd59feb63fcf40fe4baf55401baea6b4feb4
- git.kernel.org/stable/c/34eb22836e0cdba093baac66599d68c4cd245a9d
- git.kernel.org/stable/c/53f07d095e7e680c5e4569a55a019f2c0348cdc6
- git.kernel.org/stable/c/ba4811c8b433bfa681729ca42cc62b6034f223b0
- git.kernel.org/stable/c/ca97360860eb02e3ae4ba42c19b439a0fcecbf06
- git.kernel.org/stable/c/e8bfa2401d4c51eca6e48e9b33c798828ca9df61
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
- 8.8 High severity
- 9.8 Critical severity
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