Linux: Missing Release of Memory after Effective Lifetime
CVE-2026-53396 is a high-severity missing release of memory after effective lifetime vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 18cf006a08babec0bbac2a3784f8f28e56e47490, 24c975bbdd564d7d0ad90294bfa69729830345de 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 0.38% 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 18cf006a08babec0bbac2a3784f8f28e56e47490 or 24c975bbdd564d7d0ad90294bfa69729830345de, whichever matches your release line, or a later version.
- Update Linux Kernel to 7.1.3 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7ab96df840e60eb933abfe65fc5fe44e72f16dc0 up to, but not including, 18cf006a08babec0bbac2a3784f8f28e56e47490; 7ab96df840e60eb933abfe65fc5fe44e72f16dc0 up to, but not including, 24c975bbdd564d7d0ad90294bfa69729830345de; 6.19 | 18cf006a08babec0bbac2a3784f8f28e56e47490, 24c975bbdd564d7d0ad90294bfa69729830345de |
| Linux | Linux Kernel | 6.19 up to, but not including, 7.1.3 | 7.1.3 |
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
- NetworkCan be exploited remotely over a network, including the internet.
- 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
- NoneNo data is disclosed.
- Integrity
- LowLimited modification of data is possible.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix posix_acl leak and ignored error in nfsd4_create_file nfsd4_create_file() has two bugs in its ACL handling: The return value of nfsd4_acl_to_attr() is silently discarded. When the NFSv4-to-POSIX ACL conversion fails (e.g., -EINVAL for unsupported ACE types), the file is created without any ACL and the client receives NFS4_OK. This violates RFC 7530/8881 which require the server to reject unsupported attributes on CREATE. When start_creating() fails after ACL attributes have been populated in attrs (either via nfsd4_acl_to_attr or via ownership transfer from open->op_dpacl/op_pacl), the function jumps to out_write which skips nfsd_attrs_free(). The posix_acl allocations are leaked. A client can trigger this repeatedly with OPEN(CREATE), ACL attributes, and an invalid filename (e.g., longer than NAME_MAX). Fix both by capturing the nfsd4_acl_to_attr() return value and by changing the early error paths to jump to out instead of out_write. Initialize child to ERR_PTR(-EINVAL) so that end_creating() is safe to call even if start_creating() was never reached.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Missing Release of Memory after Effective Lifetime vulnerabilities
- 8.7 High severity
- 9.4 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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