Out-of-bounds write in libebml
Priority LOW 32CWE-787Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-787 and the CVSS impact.
Summary
A flaw was found in libebml before 1.4.2. A heap overflow bug exists in the implementation of EbmlString::ReadData and EbmlUnicodeString::ReadData in libebml.
Why it matters now
EPSS 0.01729 77th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed libebml: 1.4.2
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | libebml | before 1.4.2 | 1.4.2 | Patch available | CNA |
- libebml Vendor— Affected before 1.4.2 Fixed in 1.4.2 Patch available CNA
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:matroska:libebml:*:*:*:*:*:*:*:* | before 1.4.2 | Vulnerable | Matroska |
| cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* | 32 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* | 33 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
- cpe:2.3:a:matroska:libebml:*:*:*:*:*:*:*:* Versions before 1.4.2 Vulnerable ·Matroska
- cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* Versions 32 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
Remediation
- Fix · CNA libebml Fixed in 1.4.2
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-3405
- 2026-10-03 Alias added: GHSA-xc72-rxv8-3m23
References
Sources
- CVE-2021-3405 · CVE Program
- CVE-2021-3405 · NVD
- FIRST EPSS
- GHSA-xc72-rxv8-3m23 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-3405 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences