VulnerabilityPublished 27 Aug 2026

CVE-2026-80546: Linux kernel · s390/zcrypt: Improve CCA CPRB length and overflow checks

Source GCVE Database

Authoritative record:CVE-2026-80546· High 7.8

Not known to be exploited · CVSS 7.8 High · fixed in 584400144020f40365de3972c4763da520e7280e : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 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 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 584400144020f40365de3972c4763da520e7280e, 50fe5133dcb46449daf2435fa705264364411129, 35ac6754ba6da45fd193f5ce3f665f7490b830d5 +1

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-8cmf-4x36-qp8x

What to do

Upgrade Linux kernel to 584400144020f40365de3972c4763da520e7280e, 50fe5133dcb46449daf2435fa705264364411129, 35ac6754ba6da45fd193f5ce3f665f7490b830d5 or 6.13.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.12.114 <6.13	Fixed in 584400144020f40365de3972c4763da520e7280e 50fe5133dcb46449daf2435fa705264364411129 35ac6754ba6da45fd193f5ce3f665f7490b830d5 6.13
LinuxLinux	Affected =7.1	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to address this vulnerability by improving input validation and overflow checks in the s390/zcrypt code. Users should apply the official kernel updates that include these patches. Since this is not a cloud service, remediation depends on deploying the updated kernel version. Patch status is not explicitly confirmed in the provided data; users should consult the vendor or Linux kernel advisories for the exact fixed versions and update accordingly.

Description

A vulnerability in the Linux kernel's s390/zcrypt component was resolved, involving improper input validation in the xcrb_msg_to_type6cprb_msgx() function. The flaw includes integer overflows during 4-byte alignment, missing minimum size validation for user-supplied buffers, and arithmetic overflow in size sum calculations. These issues could lead to buffer overflows and uninitialized memory access. The vulnerability has a high severity score of 7.8 CVSS v3.1 and affects local attackers with low privileges. A fix has been implemented to use safer length calculations and boundary checks.

Impact

This vulnerability allows a local attacker with low privileges to cause buffer overflows and read uninitialized memory in the Linux kernel's s390/zcrypt component. The impact includes potential full confidentiality, integrity, and availability compromise of the affected system, as indicated by the CVSS vector (C:H/I:H/A:H). No known exploits in the wild have been reported.

Summary

The Linux kernel s390/zcrypt subsystem contained a vulnerability in the xcrb_msg_to_type6cprb_msgx() function due to insufficient input validation. Specifically, signed integer overflow could occur during 4-byte boundary alignment, causing undersized buffer allocations or incorrect bounds checking. Additionally, the CPRBX structure copied from userspace lacked minimum size validation, leading to potential uninitialized memory reads. Arithmetic overflow in summing control and data block sizes could bypass size checks, enabling buffer overflows. The patch replaced int with size_t for length calculations, added U32_MAX boundary checks after alignment, validated minimum control block size before copying from userspace, and detected sum calculation overflows to prevent these issues.

References

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