CVE-2025-27091: OpenH264 is a free license codec library which supports H.264 encoding and decoding

Q: How do I fix CVE-2025-27091?

openh264: upgrade to 2.5.1. Exact commands for each OS are on this page.

Q: Is CVE-2025-27091 being exploited?

CVE-2025-27091 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-27091 affect?

CVE-2025-27091 affects openh264. Severity is high (CVSS 7.5). 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 vulnera

Routine

HIGH 7.5UPGRADE

CVE-2025-27091 is a high-severity flaw (CVSS 7.5) affecting openh264. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 atta

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-122, CWE-787
Published	2025-02-20
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: cisco

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-02-20 18:15 UTCPublished CVE record published
2026-06-17 09:03 UTCUpdated Record last modified

cisco openh264 UPGRADE

Affected: < 2.5.1

Fixed in: 2.5.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy openh264 || rpm -q openh264 || openh264 --version

2. UPGRADE to 2.5.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openh264

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openh264

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-27091?

openh264: upgrade to 2.5.1. Exact commands for each OS are on this page.

Is CVE-2025-27091 being exploited?

CVE-2025-27091 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-27091 affect?

CVE-2025-27091 affects openh264. Severity is high (CVSS 7.5). 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 vulnera

How urgent is CVE-2025-27091?

Priority 39/100. High severity

Software pages

Cisco vulnerabilities

References

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