Kernel memory corruption via CTCM double free
Published Dec 4, 2025 · Updated Aug 5, 2026
Double free in the s390 CTCM driver in Linux allows attackers to corrupt kernel memory or crash the system via a crafted CTC frame. ctcmpc_unpack_skb calls mpc_rcvd_sweep_req, which frees mpcginfo, and then passes the same pointer to kfree again. Exploitation requires control of a directly attached CTC peer, such as a partner LPAR or coupled z/VM guest; the resulting heap corruption permits kernel-memory reads and writes or a repeatable crash.
Summary
What happened
Double free in the s390 CTCM driver in Linux allows attackers to corrupt kernel memory or crash the system via a crafted CTC frame. ctcmpc_unpack_skb calls mpc_rcvd_sweep_req, which frees mpcginfo, and then passes the same pointer to kfree again. Exploitation requires control of a directly attached CTC peer, such as a partner LPAR or coupled z/VM guest; the resulting heap corruption permits kernel-memory reads and writes or a repeatable crash.
The record
- CVE
- CVE-2025-40253
- Published
- Dec 4, 2025
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 4, 2025CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0c0b20587b9f25a2ad14db7f80ebe49bdf29920a <3b177b2ded563df16f6d5920671ffcfe5915d472
- Affected versionversion=0c0b20587b9f25a2ad14db7f80ebe49bdf29920a <43096dab8cc60fc39133205fd149a54d3acebea8
- Affected versionversion=0c0b20587b9f25a2ad14db7f80ebe49bdf29920a <7ff76f8dc6b550f8d16487bf3cebc278be720b5c
- Affected versionversion=0c0b20587b9f25a2ad14db7f80ebe49bdf29920a <b9dbfb1b5699f9f1e4991f96741bdf9047147589
- Affected versionversion=0c0b20587b9f25a2ad14db7f80ebe49bdf29920a <da02a1824884d6c84c5e5b5ac373b0c9e3288ec2
- Affected versionversion=2bd57101c3ecf3f8c0da1d26c2b6ad511adc6d50 <7616e2eee679746d526c7f5befd4eedb995935b5
- Affected versionversion=36933de59f67029e5739a98393891f9b94f27e0f
- Affected versionversion=4.14.280 <4.15
- Affected versionversion=4.19.244 <4.20
- Affected versionversion=467ddbbe7e749d558f13e640f50f546149c930b3 <06f1dd1de0d33dbfbd2e1fc9fc57d8895f730de2
- Affected versionversion=4.9.315 <4.10
- Affected versionversion=4c9ba0fed125deba8416b995b0c274b0804c0c24
- Affected versionversion=4d3c6d741816539b57fa1110c3f765a8c176d7b4 <6bf8ccaabce8cebb6cb1f255c93d0acdfe95c17a
- Affected versionversion=5.10.117 <5.10.247
- Affected versionversion=5.15.41 <5.15.197
- Affected versionversion=5.17.9 <5.18
- Affected versionversion=5.18
- Affected versionversion=5.4.195 <5.4.302
- Affected versionversion=d886b4292a1c5b4facdb2dfdc31f0fecc71df898
- Affected versionversion=ea0053af5dab4d63a9c44563973fb2f3bfd9eb2b
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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