Linux: Use After Free
CVE-2025-40149 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 2b1bef126bbb8d0da51491357559126d567c1dee, e37ca0092ddace60833790b4ad7a390408fb1be9, 13159c7125636371543a82cb7bbae00ab36730cc 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 0.17% 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 2b1bef126bbb8d0da51491357559126d567c1dee or e37ca0092ddace60833790b4ad7a390408fb1be9 or 13159c7125636371543a82cb7bbae00ab36730cc or f09cd209359a23f88d4f3fa3d2379d057027e53c, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.199 or 6.1.161 or 6.6.121 or 6.12.66, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e8f69799810c32dd40c6724d829eccc70baad07f up to, but not including, 2b1bef126bbb8d0da51491357559126d567c1dee; e8f69799810c32dd40c6724d829eccc70baad07f up to, but not including, e37ca0092ddace60833790b4ad7a390408fb1be9; e8f69799810c32dd40c6724d829eccc70baad07f up to, but not including, 13159c7125636371543a82cb7bbae00ab36730cc; e8f69799810c32dd40c6724d829eccc70baad07f up to, but not including, f09cd209359a23f88d4f3fa3d2379d057027e53c; e8f69799810c32dd40c6724d829eccc70baad07f up to, but not including, feb474ddbf26b51f462ae2e60a12013bdcfc5407; e8f69799810c32dd40c6724d829eccc70baad07f up to, but not including, c65f27b9c3be2269918e1cbad6d8884741f835c5; 4.18 | 2b1bef126bbb8d0da51491357559126d567c1dee, e37ca0092ddace60833790b4ad7a390408fb1be9, 13159c7125636371543a82cb7bbae00ab36730cc, f09cd209359a23f88d4f3fa3d2379d057027e53c, feb474ddbf26b51f462ae2e60a12013bdcfc5407, c65f27b9c3be2269918e1cbad6d8884741f835c5 |
| 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 | 4.18 up to, but not including, 5.15.199; 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, 6.17.3 | 5.15.199, 6.1.161, 6.6.121, 6.12.66, 6.17.3 |
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: tls: Use __sk_dst_get() and dst_dev_rcu() in get_netdev_for_sock(). get_netdev_for_sock() is called during setsockopt(), so not under RCU. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dst_dev_rcu(). Note that the only ->ndo_sk_get_lower_dev() user is bond_sk_get_lower_dev(), which uses RCU.
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/13159c7125636371543a82cb7bbae00ab36730cc
- git.kernel.org/stable/c/2b1bef126bbb8d0da51491357559126d567c1dee
- git.kernel.org/stable/c/c65f27b9c3be2269918e1cbad6d8884741f835c5
- git.kernel.org/stable/c/e37ca0092ddace60833790b4ad7a390408fb1be9
- git.kernel.org/stable/c/f09cd209359a23f88d4f3fa3d2379d057027e53c
- git.kernel.org/stable/c/feb474ddbf26b51f462ae2e60a12013bdcfc5407
Other references
Recent Use After Free vulnerabilities
- 7.8 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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