Linux: Missing Release of Memory after Effective Lifetime
CVE-2025-39963 is a high-severity missing release of memory after effective lifetime 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 a89c34babc2e5834aa0905278f26f4dbe4b26b76, 50a98ce1ea694f1ff8e87bc2f8f84096d1736f6a, 2c139a47eff8de24e3350dadb4c9d5e3426db826 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 0.16% 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 a89c34babc2e5834aa0905278f26f4dbe4b26b76 or 50a98ce1ea694f1ff8e87bc2f8f84096d1736f6a or 2c139a47eff8de24e3350dadb4c9d5e3426db826, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.49 or 6.16.9, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6fe4220912d19152a26ce19713ab232f4263018d up to, but not including, a89c34babc2e5834aa0905278f26f4dbe4b26b76; 6fe4220912d19152a26ce19713ab232f4263018d up to, but not including, 50a98ce1ea694f1ff8e87bc2f8f84096d1736f6a; 6fe4220912d19152a26ce19713ab232f4263018d up to, but not including, 2c139a47eff8de24e3350dadb4c9d5e3426db826; 6.10 | a89c34babc2e5834aa0905278f26f4dbe4b26b76, 50a98ce1ea694f1ff8e87bc2f8f84096d1736f6a, 2c139a47eff8de24e3350dadb4c9d5e3426db826 |
| Linux | Linux Kernel | 6.10 up to, but not including, 6.12.49; 6.13 up to, but not including, 6.16.9; 6.17 | 6.12.49, 6.16.9 |
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: io_uring: fix incorrect io_kiocb reference in io_link_skb In io_link_skb function, there is a bug where prev_notif is incorrectly assigned using 'nd' instead of 'prev_nd'. This causes the context validation check to compare the current notification with itself instead of comparing it with the previous notification. Fix by using the correct prev_nd parameter when obtaining prev_notif.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Release of Memory after Effective Lifetime
The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
How developers prevent this class of flaw
- Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone. For example, glibc in Linux provides protection against free of invalid pointers. When using Xcode to target OS X or iOS, enable automatic reference counting (ARC). To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Consider using the Boehm-Demers-Weiser garbage collector (bdwgc), which can help avoid leaks.
More Missing Release of Memory after Effective Lifetime vulnerabilities (CWE-401)
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
Recent Missing Release of Memory after Effective Lifetime vulnerabilities
- 7.8 High severity
- 7.5 High severity
- 8.6 High severity
- 8.6 High severity
- 7.5 High severity
- 7.5 High severity
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