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

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-04 · updated 2026-10-19

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.

Affected products

• Linux kernel: from 5.4.195 before 5.4.302; from 5.10.117 before 5.10.247; from 5.15.41 before 5.15.197; from 4.9.315 before 4.10; from 4.14.280 before 4.15; from 4.19.244 before 4.20 — fixed in 4.10, 4.15, 4.20, 5.10.247, 5.15.197, 5.18

How to fix

Upgrade to a fixed version: Linux kernel 4.10, 4.15, 4.20, 5.10.247. Check the vendor advisory for mitigations.

References

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

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