s390/zcrypt: Improve EP11 CPRB domain handling with ASN.1 parsing
CVE-2026-80544 · published 26 Aug 2026
How serious is it
- Severity: high, CVSS score 7.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-80544?
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Who is affected
- Linux Linux: 20b0b0159390fa5c00a435195649680fefda81e0 to < 00a44ff06bcffb68b9cd7e90d2259b7d14b82b18, e2c6d91eb8b1533753755f07803e47eceed263d0 to < db21b2cf6dd0af5ffd08931e0a9fcda5a0473220, e2c6d91eb8b1533753755f07803e47eceed263d0 to < 0864a163783bff109b548266921829ea794edc93, f9da85d4780515f65983e0af151458599adaef3d
- Linux Linux: 7.1
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
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- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
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.
Check your whole app
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References
- git.kernel.org/stable/c/00a44ff06bcffb68b9cd7e90d2259b7d14b82b18
- git.kernel.org/stable/c/db21b2cf6dd0af5ffd08931e0a9fcda5a0473220
- git.kernel.org/stable/c/0864a163783bff109b548266921829ea794edc93
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON