CVE-2025-11187

MEDIUM

OpenSSL 3.4.0-3.4.3, 3.5.0-3.5.4, 3.6.0 - Stack-based Buffer Overflow in PKCS#12 PBMAC1 MAC Verification

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2025-11187. PoCs published by metadust.

AI-analyzed exploit summary This repository contains functional exploit code for CVE-2025-11187, demonstrating a vulnerability in OpenSSL 3.6.0 related to PKCS12 MAC verification. The PoC triggers an overflow by setting an intentionally large key length during PBKDF2 parameter manipulation.

Description

Issue summary: PBMAC1 parameters in PKCS#12 files are missing validation which can trigger a stack-based buffer overflow, invalid pointer or NULL pointer dereference during MAC verification. Impact summary: The stack buffer overflow or NULL pointer dereference may cause a crash leading to Denial of Service for an application that parses untrusted PKCS#12 files. The buffer overflow may also potentially enable code execution depending on platform mitigations. When verifying a PKCS#12 file that uses PBMAC1 for the MAC, the PBKDF2 salt and keylength parameters from the file are used without validation. If the value of keylength exceeds the size of the fixed stack buffer used for the derived key (64 bytes), the key derivation will overflow the buffer. The overflow length is attacker-controlled. Also, if the salt parameter is not an OCTET STRING type this can lead to invalid or NULL pointer dereference. Exploiting this issue requires a user or application to process a maliciously crafted PKCS#12 file. It is uncommon to accept untrusted PKCS#12 files in applications as they are usually used to store private keys which are trusted by definition. For this reason the issue was assessed as Moderate severity. The FIPS modules in 3.6, 3.5 and 3.4 are not affected by this issue, as PKCS#12 processing is outside the OpenSSL FIPS module boundary. OpenSSL 3.6, 3.5 and 3.4 are vulnerable to this issue. OpenSSL 3.3, 3.0, 1.1.1 and 1.0.2 are not affected by this issue as they do not support PBMAC1 in PKCS#12.

Exploits (1)

nomisec WORKING POC
by metadust · poc
https://github.com/metadust/CVE-2025-11187

This repository contains functional exploit code for CVE-2025-11187, demonstrating a vulnerability in OpenSSL 3.6.0 related to PKCS12 MAC verification. The PoC triggers an overflow by setting an intentionally large key length during PBKDF2 parameter manipulation.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: OpenSSL 3.6.0
No auth needed
Prerequisites: OpenSSL 3.6.0 source code · clang with ASan/UBSan
devstral-2 · analyzed Mar 16, 2026 Full analysis →

Scores

CVSS v3 6.1
EPSS 0.0052
EPSS Percentile 39.6%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact total

Details

CWE
CWE-787 CWE-476
Status published
Products (4)
openssl/openssl 3.4.0 - 3.4.4
OpenSSL/OpenSSL 3.4.0 - 3.4.4
OpenSSL/OpenSSL 3.5.0 - 3.5.5
OpenSSL/OpenSSL 3.6.0 - 3.6.1
Published Jan 27, 2026
Tracked Since Feb 18, 2026