Kernel memory corruption via mismatched reused-buffer length
Published Aug 15, 2026 · Updated Aug 15, 2026
Out-of-bounds write in Linux s390 monwriter allows local users to corrupt kernel memory by reusing a data buffer with a new length. The monwrite_write path derives the copy count from the stored header but the destination offset from the new header without checking that their datalen fields match. Reachability requires a Linux s390 z/VM guest and root-only write access to /dev/monwriter by default; exploitation can corrupt the kernel heap and interrupt the guest.
Summary
What happened
Out-of-bounds write in Linux s390 monwriter allows local users to corrupt kernel memory by reusing a data buffer with a new length. The monwrite_write path derives the copy count from the stored header but the destination offset from the new header without checking that their datalen fields match. Reachability requires a Linux s390 z/VM guest and root-only write access to /dev/monwriter by default; exploitation can corrupt the kernel heap and interrupt the guest.
The record
- CVE
- CVE-2026-72025
- Published
- Aug 15, 2026
- Updated
- Aug 15, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-787, T1499.004
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Aug 15, 2026CVE publishedPublication date reported by the CVE source.
- Aug 15, 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=0 <5.10.261
- Affected versionversion=0 <5.15.212
- Affected versionversion=0 <6.1.178
- Affected versionversion=0 <6.12.97
- Affected versionversion=0 <6.18.40
- Affected versionversion=0 <6.6.145
- Affected versionversion=0 <7.1.5
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <01f3ce411711c2c919598ea25320a5a48f71edbc
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <036bc5661060702e798d215e81bb46da530965b3
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <096dff1247037d329c04b3a5be0ecdfb1c5c7ac6
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2995ccec260caa9e85b3301a4aba1e66ed80ad74
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <759d91378203ea35fa9bca6726dcf0010de081fb
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ae5347f3db1782c6118f6cc0d9fd8b1d43397db3
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d39cf4a6d721b1ae21eb53bbf3e8cd984253d7ab
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f0745496f7c171271cafd9457df3b914a483ddeb
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Upstream monwriter concrete exploitation sequenceproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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