Linux: Use After Free
CVE-2025-38471 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 730fed2ff5e259495712518e18d9f521f61972bb, 1f3a429c21e0e43e8b8c55d30701e91411a4df02, cdb767915fc9a15d88d19d52a1455f1dc3e5ddc8 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 0.47% 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 730fed2ff5e259495712518e18d9f521f61972bb or 1f3a429c21e0e43e8b8c55d30701e91411a4df02 or cdb767915fc9a15d88d19d52a1455f1dc3e5ddc8 or c76f6f437c46b2390888e0e1dc7aafafa9f4e0c6, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1 or 6.1.147 or 6.6.100 or 6.12.40, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0d87bbd39d7fd1135ab9eca672d760470f6508e8 up to, but not including, 730fed2ff5e259495712518e18d9f521f61972bb; 0d87bbd39d7fd1135ab9eca672d760470f6508e8 up to, but not including, 1f3a429c21e0e43e8b8c55d30701e91411a4df02; 0d87bbd39d7fd1135ab9eca672d760470f6508e8 up to, but not including, cdb767915fc9a15d88d19d52a1455f1dc3e5ddc8; 0d87bbd39d7fd1135ab9eca672d760470f6508e8 up to, but not including, c76f6f437c46b2390888e0e1dc7aafafa9f4e0c6; 0d87bbd39d7fd1135ab9eca672d760470f6508e8 up to, but not including, 4ab26bce3969f8fd925fe6f6f551e4d1a508c68b; 2277d7cbdf47531b2c3cd01ba15255fa955aab35; 6.0.6 up to, but not including, 6.1; 6.1 | 730fed2ff5e259495712518e18d9f521f61972bb, 1f3a429c21e0e43e8b8c55d30701e91411a4df02, cdb767915fc9a15d88d19d52a1455f1dc3e5ddc8, c76f6f437c46b2390888e0e1dc7aafafa9f4e0c6, 4ab26bce3969f8fd925fe6f6f551e4d1a508c68b, 6.1 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | V3.1.5 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | V3.1.5 and later | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP | V3.1.5 and later | Not stated |
| Linux | Linux Kernel | 6.0.6 up to, but not including, 6.1; 6.1.1 up to, but not including, 6.1.147; 6.2 up to, but not including, 6.6.100; 6.7 up to, but not including, 6.12.40; 6.13 up to, but not including, 6.15.8; 6.1; 6.16 | 6.1, 6.1.147, 6.6.100, 6.12.40, 6.15.8 |
| Debian | Debian Linux | 11.0 | Not stated |
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 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: tls: always refresh the queue when reading sock After recent changes in net-next TCP compacts skbs much more aggressively. This unearthed a bug in TLS where we may try to operate on an old skb when checking if all skbs in the queue have matching decrypt state and geometry. BUG: KASAN: slab-use-after-free in tls_strp_check_rcv+0x898/0x9a0 [tls] (net/tls/tls_strp.c:436 net/tls/tls_strp.c:530 net/tls/tls_strp.c:544) Read of size 4 at addr ffff888013085750 by task tls/13529 CPU: 2 UID: 0 PID: 13529 Comm: tls Not tainted 6.16.0-rc5-virtme Call Trace: kasan_report+0xca/0x100 tls_strp_check_rcv+0x898/0x9a0 [tls] tls_rx_rec_wait+0x2c9/0x8d0 [tls] tls_sw_recvmsg+0x40f/0x1aa0 [tls] inet_recvmsg+0x1c3/0x1f0 Always reload the queue, fast path is to have the record in the queue when we wake, anyway (IOW the path going down "if !strp->stm.full_len").
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/1f3a429c21e0e43e8b8c55d30701e91411a4df02
- git.kernel.org/stable/c/4ab26bce3969f8fd925fe6f6f551e4d1a508c68b
- git.kernel.org/stable/c/730fed2ff5e259495712518e18d9f521f61972bb
- git.kernel.org/stable/c/c76f6f437c46b2390888e0e1dc7aafafa9f4e0c6
- git.kernel.org/stable/c/cdb767915fc9a15d88d19d52a1455f1dc3e5ddc8
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlThird Party Advisory
Other references
Recent Use After Free vulnerabilities
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