CVE-2026-39853
osslsigncode has a Stack Buffer Overflow via Unbounded Digest Copy During Signature Verification
Description
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.
INFO
Published Date :
April 9, 2026, 4:16 p.m.
Last Modified :
Oct. 26, 2026, 9:10 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-39853
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update osslsigncode to version 2.12 or later.
- Verify signature verification paths are secure.
- Validate digest lengths before copying.
- Avoid unbounded memcpy operations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39853.
| URL | Resource |
|---|---|
| https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943ed8144db68 | Patch |
| https://github.com/mtrojnar/osslsigncode/releases/tag/2.12 | Product Release Notes |
| https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4 | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39853 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39853
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39853 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39853 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: osslsigncode de mtrojnar, Description: osslsigncode es una herramienta que implementa la firma y el sellado de tiempo Authenticode. Anterior a la 2.12, existe una vulnerabilidad de desbordamiento de búfer de pila en osslsigncode en varias rutas de verificación de firma. Durante la verificación de una firma PKCS#7, el código copia el valor de resumen de una estructura SpcIndirectDataContent analizada en un búfer de pila de tamaño fijo (mdbuf[EVP_MAX_MD_SIZE], 64 bytes) sin validar que la longitud de origen encaje dentro del búfer de destino. Este patrón está presente en los manejadores de verificación para archivos PE, MSI, CAB y de script. Un atacante puede crear un archivo firmado malicioso con un campo de resumen sobredimensionado en SpcIndirectDataContent. Cuando un usuario verifica dicho archivo con osslsigncode verify, el memcpy sin límites puede desbordar el búfer de pila y corromper el estado de pila adyacente. Esta vulnerabilidad está corregida en la 2.12. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'mtrojnar', 'product': 'osslsigncode', 'versions': [{'status': 'affected', 'version': '< 2.12'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-39853', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-04-09T16:13:50.325421Z'} -
Initial Analysis by [email protected]
Apr. 17, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:osslsigncode_project:osslsigncode:*:*:*:*:*:*:*:* versions up to (excluding) 2.12 Added Reference Type GitHub, Inc.: https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943ed8144db68 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/mtrojnar/osslsigncode/releases/tag/2.12 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4 Types: Vendor Advisory -
New CVE Received by [email protected]
Apr. 09, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-787 Added CWE CWE-121 Added Reference https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943ed8144db68 Added Reference https://github.com/mtrojnar/osslsigncode/releases/tag/2.12 Added Reference https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4