Cisco OpenH264 up to 2.5.x Decoding heap-based overflow

Summaryinfo

A vulnerability classified as critical has been found in Cisco OpenH264 up to 2.5.x. The impacted element is an unknown function of the component Decoding. The manipulation leads to heap-based overflow. This vulnerability is referenced as CVE-2025-27091. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Cisco OpenH264 up to 2.5.x. This issue affects some unknown processing of the component Decoding. The manipulation with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

OpenH264 is a free license codec library which supports H.264 encoding and decoding. A vulnerability in the decoding functions of OpenH264 codec library could allow a remote, unauthenticated attacker to trigger a heap overflow. This vulnerability is due to a race condition between a Sequence Parameter Set (SPS) memory allocation and a subsequent non Instantaneous Decoder Refresh (non-IDR) Network Abstraction Layer (NAL) unit memory usage. An attacker could exploit this vulnerability by crafting a malicious bitstream and tricking a victim user into processing an arbitrary video containing the malicious bistream. An exploit could allow the attacker to cause an unexpected crash in the victim's user decoding client and, possibly, perform arbitrary commands on the victim's host by abusing the heap overflow. This vulnerability affects OpenH264 2.5.0 and earlier releases. Both Scalable Video Coding (SVC) mode and Advanced Video Coding (AVC) mode are affected by this vulnerability. OpenH264 software releases 2.6.0 and later contained the fix for this vulnerability. Users are advised to upgrade. There are no known workarounds for this vulnerability. ### For more information If you have any questions or comments about this advisory: * [Open an issue in cisco/openh264](https://github.com/cisco/openh264/issues) * Email Cisco Open Source Security ([[email protected]](mailto:[email protected])) and Cisco PSIRT ([[email protected]](mailto:[email protected])) ### Credits: * **Research:** Octavian Guzu and Andrew Calvano of Meta * **Fix ideation:** Philipp Hancke and Shyam Sadhwani of Meta * **Fix implementation:** Benzheng Zhang (@BenzhengZhang) * **Release engineering:** Benzheng Zhang (@BenzhengZhang)

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2025-27091 since 02/18/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 02/27/2025).

The vulnerability scanner Nessus provides a plugin with the ID 216859 (Debian dsa-5870 : libopenh264-7 - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.6.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (216859). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• Cisco

Name

• OpenH264

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5

License

• commercial

Website

• Vendor: https://www.cisco.com/
• Product: https://github.com/cisco/openh264/

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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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