CVE-2025-11187 Improper validation of PBMAC1 parameters in PKCS#12 MAC verification
Attacker can cause denial of service or potential code execution by crafting a malicious PKCS#12 file with invalid PBMAC1 parameters.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-11187?
CVE-2025-11187 is a medium-severity memory corruption vulnerability in Openssl Openssl, published on 27 Jan 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2025-11187?
It affects 1 product.
Products include Openssl Openssl.
How do I fix CVE-2025-11187?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-11187 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-11187 exists.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Openssl Openssl
Sources
Also known as ALPINE-CVE-2025-11187, BELL-CVE-2025-11187, CLEANSTART-2026-PD89526, CLEANSTART-2026-VP72640, DEBIAN-CVE-2025-11187, GHSA-hpc7-gcqm-58fv and 4 more.