CVE-2026-80555

Host memory exhaustion via incomplete vfio-ccw cleanup

Published Aug 26, 2026 · Updated Aug 27, 2026

Memory leak in s390 vfio-ccw allows guest OS users to exhaust host memory via crafted multi-TIC channel programs. When cp_init() fails after allocating several TIC-linked ccwchain segments, ccwchain_handle_ccw() frees only the current segment while cp_free() remains disabled, orphaning earlier kernel allocations. Exploitation requires an s390 KVM guest with a vfio-ccw passthrough device; repeated guest I/O can cause host-wide out-of-memory denial of service without disclosing or modifying data.

CVSS severity7.1
High
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in s390 vfio-ccw allows guest OS users to exhaust host memory via crafted multi-TIC channel programs. When cp_init() fails after allocating several TIC-linked ccwchain segments, ccwchain_handle_ccw() frees only the current segment while cp_free() remains disabled, orphaning earlier kernel allocations. Exploitation requires an s390 KVM guest with a vfio-ccw passthrough device; repeated guest I/O can cause host-wide out-of-memory denial of service without disclosing or modifying data.

The record

CVE
CVE-2026-80555
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 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.

  1. Affected versionversion=5.3
  2. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <152fcb74a26804b70909381c6acc90595a0ae1c1
  3. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <17e01e342af74de12899c206dcc9ec90684703aa
  4. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <276bd7ed34d56c48c65c43c0b08f2ee77029b2fa
  5. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <32e3d364a7b8295120d37e6a6bd433d2de26f748
  6. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <4699b54fada156534cbb39834d47fc9374d7a1f5
  7. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <6a917199aaf97904f5619afe3dfdacb155b03e8c
  8. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <74186c2968f8f756ac3226b545b598457c910c75
  9. Affected versionversion=8b515be512a2435bb8aedc6390cbe140167f9eb9 <f9bcff265556796834122f95de16d52a8375206c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.3; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <152fcb74a26804b70909381c6acc90595a0ae1c1; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <17e01e342af74de12899c206dcc9ec90684703aa; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <276bd7ed34d56c48c65c43c0b08f2ee77029b2fa; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <32e3d364a7b8295120d37e6a6bd433d2de26f748; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <4699b54fada156534cbb39834d47fc9374d7a1f5; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <6a917199aaf97904f5619afe3dfdacb155b03e8c; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <74186c2968f8f756ac3226b545b598457c910c75; version=8b515be512a2435bb8aedc6390cbe140167f9eb9 <f9bcff265556796834122f95de16d52a8375206c

Published CVSS scores

7.1Linux kernel CVE teamCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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