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CVE-2026-80545 (GCVE-0-2026-80545)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 05:01
VLAI
Title
s390/zcrypt: Improve EP11 CPRB length and overflow checks
Summary
In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Improve EP11 CPRB length and overflow checks The xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Missing minimum size validation: The ep11_cprb structure and subsequent payload fields (pld_tag, pld_lenfmt) are copied from userspace without verifying sufficient buffer length. 2. Arithmetic overflow in length calculations: CEIL4 alignment could overflow, bypassing size checks and enabling buffer overflows. 3. The payload is asn1 encoded but the function just uses a simple c struct overlay to access some fields of the payload. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, and validating minimum request size and minimum reply size before copying from userspace. Do a very simple asn1 parsing of the payload up to the function value field.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 2976b9d2e716c7e5487ca7c29a7bd076cf9adf08 (git)
Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 17ac0bc866fc624cd05f022dcd8b730c0af11bb1 (git)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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              "value": "AV:L - The flaw is reached only via local ioctl(ZSENDEP11CPRB) on /dev/z90crypt or administrator-created zcdn device nodes on IBM Z systems with EP11 crypto hardware; there is no network, Bluetooth, or USB packet path to this code.\nAC:L - The attacker fully controls ep11_urb req_len, req, and resp_len in the ioctl argument; near-SIZE_MAX lengths can wrap CEIL4 sum checks to bypass bufsize validation and trigger deterministic heap corruption without races or external timing dependencies.\nPR:L - Exploitation requires opening a zcrypt device and passing zcrypt_check_ioctl, access routinely delegated to non-root application/service accounts via zcdn nodes on shared IBM Z cloud, LPAR, and container deployments that grant EP11 CPRB ioctl permissions.\nUI:N - Triggering is self-contained by submitting a crafted EP11 request block through ioctl; no victim interaction, file opening by another user, or administrative action beyond having zcrypt device access is required.\nS:U - Impact is kernel heap corruption and privilege escalation within the same Linux security authority on the s390 host; it does not cross VM, IOMMU, or container sandbox boundaries to affect a separate security domain.\nC:H - Undersized copies leave uninitialized kmalloc data readable via struct overlays on pld_lenfmt and payload_hdr, while integer-overflowed req_len values enable copy_from_user far beyond the ap_msg buffer, providing arbitrary kernel memory disclosure primitives.\nI:H - Missing minimum-size and U32_MAX boundary checks let attacker-controlled lengths bypass ap_msg-\u003elen validation and corrupt adjacent kmalloc objects in the crypto message buffer, enabling heap control primitives and potential arbitrary kernel code execution.\nA:H - Heap buffer overflow and out-of-bounds parsing of EP11 CPRB payloads can cause kernel oops, panic, or denial of crypto services on mission-critical IBM Z systems; memory corruption alone threatens host availability even before full exploitation."
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}



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