CVE-2026-80554: Linux kernel · s390/vfio_ccw: Limit the number of channel program segments
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.3 Critical · fixed in a1625f66eaa1200068a0e2c05bc90e65182fc4e3 : patch Linux kernel as a priority.
Data as of 30 Oct 2026, 12:49 UTC
Thin evidence
One scorer or none| CNA (Linux) | CVSS 3.1 | 9.3 |
|---|
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in a1625f66eaa1200068a0e2c05bc90e65182fc4e3, 5405c90d6a47b3014e74ee0618a162449abbbc93, 15fb4559a7fdf0b8725e433a71cfd03a1313a48b +3
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 26 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Limit the number of channel program segments The processing of channel programs, and the CCWs within them, is done recursively. As such, there is an arbitrary (but not architectural) limit to the number of CCWs that can exist in a single channel program. The vfio-ccw logic breaks these channel programs into segments whenever it encounters a Transfer-In-Channel (TIC) CCW, and the combined number of segments count towards the global limit. Impose an equivalent limit to the number of segments until such logic can be made non-recursive.
References
- git.kernel.org/stable/c/2ce00bb19db13606cda79f4b7aae4d9775de3096 (opens in a new tab)
- git.kernel.org/stable/c/15fb4559a7fdf0b8725e433a71cfd03a1313a48b (opens in a new tab)
- git.kernel.org/stable/c/a1625f66eaa1200068a0e2c05bc90e65182fc4e3 (opens in a new tab)
- git.kernel.org/stable/c/06f4d6e5a8af6c2072e8cd39dbc512c683ca7fb2 (opens in a new tab)
- git.kernel.org/stable/c/4ee94790490ae8dcc97df8597f07836c8a81bbcf (opens in a new tab)
- git.kernel.org/stable/c/5405c90d6a47b3014e74ee0618a162449abbbc93 (opens in a new tab)