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VulnerabilityPublished Updated

CVE-2026-80544: Linux kernel · s390/zcrypt: Improve EP11 CPRB domain handling with ASN.1 parsing

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in db21b2cf6dd0af5ffd08931e0a9fcda5a0473220 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
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 db21b2cf6dd0af5ffd08931e0a9fcda5a0473220, 0864a163783bff109b548266921829ea794edc93, 6.13 +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 26 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 26 Oct 2026.

What to do

Upgrade Linux kernel to db21b2cf6dd0af5ffd08931e0a9fcda5a0473220, 0864a163783bff109b548266921829ea794edc93, 6.13 or 00a44ff06bcffb68b9cd7e90d2259b7d14b82b18.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • >=6.12.114 <6.13
Fixed in
  • db21b2cf6dd0af5ffd08931e0a9fcda5a0473220
  • 0864a163783bff109b548266921829ea794edc93
  • 6.13
  • 00a44ff06bcffb68b9cd7e90d2259b7d14b82b18
LinuxLinuxAffected
  • =7.1
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Improve EP11 CPRB domain handling with ASN.1 parsing The zcrypt_msgtype6_send_ep11_cprb() function uses fragile struct overlays to access and modify the domain field in the EP11 CPRB payload, creating maintainability and security concerns: 1. Struct overlay approach (pld_hdr) assumes fixed payload structure and doesn't validate the actual ASN.1 encoding. 2. Complex length format detection logic is error-prone and doesn't properly validate bounds at each parsing step. 3. Direct struct member access bypasses proper ASN.1 validation. Fix by replacing struct overlays with explicit ASN.1 parsing that validates each field (payload tag/length, function tag/length/value, optional domain tag/length/value) with proper bounds checking at every step. Add asn1_int_encode() helper function to safely write integer values with correct endianness conversion. This makes the code consistent with the validation pattern introduced with the rework of the xcrb_msg_to_type6_ep11cprb_msgx() function.

References

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