CVE-2025-21641
MEDIUMCVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
3Description
In the Linux kernel, the following vulnerability has been resolved: mptcp: sysctl: blackhole timeout: avoid using current->nsproxy As mentioned in the previous commit, using the 'net' structure via 'current' is not recommended for different reasons: - Inconsistency: getting info from the reader's/writer's netns vs only from the opener's netns. - current->nsproxy can be NULL in some cases, resulting in an 'Oops' (null-ptr-deref), e.g. when the current task is exiting, as spotted by syzbot [1] using acct(2). The 'pernet' structure can be obtained from the table->data using container_of().
Analysis
In the Linux kernel, the following vulnerability has been resolved: mptcp: sysctl: blackhole timeout: avoid using current->nsproxy As mentioned in the previous commit, using the 'net' structure via. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
Technical Context
This vulnerability is classified as NULL Pointer Dereference (CWE-476), which allows attackers to crash the application by dereferencing a null pointer. In the Linux kernel, the following vulnerability has been resolved: mptcp: sysctl: blackhole timeout: avoid using current->nsproxy As mentioned in the previous commit, using the 'net' structure via 'current' is not recommended for different reasons: - Inconsistency: getting info from the reader's/writer's netns vs only from the opener's netns. - current->nsproxy can be NULL in some cases, resulting in an 'Oops' (null-ptr-deref), e.g. when the current task is exiting, as spotted by syzbot [1] using acct(2). The 'pernet' structure can be obtained from the table->data using container_of(). Affected products include: Linux Linux Kernel.
Affected Products
Linux Linux Kernel.
Remediation
A vendor patch is available. Apply the latest security update as soon as possible. Check pointers before dereferencing. Use static analysis tools to detect null pointer paths.
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External POC / Exploit Code
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