EUVD-2026-20942
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Description
osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow vulnerability exists in osslsigncode in several signature verification paths. During verification of a PKCS#7 signature, the code copies the digest value from a parsed SpcIndirectDataContent structure into a fixed-size stack buffer (mdbuf[EVP_MAX_MD_SIZE], 64 bytes) without validating that the source length fits within the destination buffer. This pattern is present in the verification handlers for PE, MSI, CAB, and script files. An attacker can craft a malicious signed file with an oversized digest field in SpcIndirectDataContent. When a user verifies such a file with osslsigncode verify, the unbounded memcpy can overflow the stack buffer and corrupt adjacent stack state. This vulnerability is fixed in 2.12.
Analysis
Stack buffer overflow in osslsigncode <2.12 allows local attackers to execute arbitrary code during signature verification. The vulnerability affects PE, MSI, CAB, and script file verification handlers that copy digest values from SpcIndirectDataContent structures into fixed 64-byte stack buffers without length validation. …
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Remediation
Within 24 hours: Identify all systems running osslsigncode and document current installed versions using package managers or vendor tools. Within 7 days: Contact osslsigncode maintainers to confirm patch timeline and interim guidance; restrict file verification operations to trusted sources only. …
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