CVE-2025-27091
OpenH264 Decoding Functions Heap Overflow Vulnerability
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
- Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Active
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
OpenH264 Decoding Functions Heap Overflow Vulnerability
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
- Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
- Record
CVE-2025-27091- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-122
- Updated
- 2026-11-02
EUVDEUVD-2025-5088
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
- Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
- Record
EUVD-2025-5088- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
NVD
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
- Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
- Record
CVE-2025-27091- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-122, CWE-787
- Updated
- 2026-11-02
OSVALPINE-CVE-2025-27091
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
- Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
- Record
ALPINE-CVE-2025-27091- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-03
OSV
OpenH264 Decoding Functions Heap Overflow Vulnerability
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
- Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
- Record
CVE-2025-27091- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-122
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2025-27091
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 * Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
- Record
DEBIAN-CVE-2025-27091- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2025-27091
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 * Email Cisco Open Source Security ([email protected]) and Cisco PSIRT ([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)
- Record
UBUNTU-CVE-2025-27091- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
openh264Alpine:v3.21 |
before 2.6.0-r0 | 2.6.0-r0 |
openh264Alpine:v3.22 |
before 2.6.0-r0 | 2.6.0-r0 |
openh264Alpine:v3.23 |
before 2.6.0-r0 | 2.6.0-r0 |
openh264Alpine:v3.24 |
before 2.6.0-r0 | 2.6.0-r0 |
openh264Debian:12 |
before 2.3.1+dfsg-3+deb12u1, plus listed versions 2.3.1+dfsg-3 |
2.3.1+dfsg-3+deb12u1 |
openh264Debian:13 |
before 2.5.0+dfsg-2 | 2.5.0+dfsg-2 |
openh264Debian:14 |
before 2.5.0+dfsg-2 | 2.5.0+dfsg-2 |
openh264Ubuntu:22.04:LTS |
All versions, plus listed versions 2.1.1+dfsg-12.1.1+dfsg-22.2.0+dfsg-12.2.0+dfsg-2 |
None known |
openh264Ubuntu:24.04:LTS |
All versions, plus listed versions 2.3.1+dfsg-32.3.1+dfsg-42.4.0+dfsg-12.4.1+dfsg-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | OSV | |
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-27091 is a high vulnerability (CVSS 8.6) in Cisco Openh264, published February 20, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.69%, the 52nd percentile. Fixed in openh264 2.6.0-r0.
References
github.com/cisco/openh264/security/advisories/GHSA-m99q-5j7x-7m9x
security.alpinelinux.org/vuln/CVE-2025-27091
nvd.nist.gov/vuln/detail/CVE-2025-27091
security-tracker.debian.org/tracker/CVE-2025-27091
ubuntu.com/security/CVE-2025-27091
cve.org/CVERecord?id=CVE-2025-27091