GStreamer H266 Codec Parsing Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of GStreamer. Interaction with this library is required to exploit this vulnerability but attack vectors may vary depending on the implementation. The specific flaw exists within the parsing of H266 sei messages. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-27381.
Conclusion & alert: CVE-2025-6663 is rated Moderate Risk (44/100): CVSS High severity, with low exploitation likelihood (EPSS 0.16%). Mandatory action: Review affected assets and schedule remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-05-03 | 0.06% | 0.16% | +0.10% |
| 2 | 2026-03-23 | 0.04% | 0.06% | +0.02% |
| 3 | 2025-11-29 | — | 0.04% | — |
Full EPSS history (5 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.8 | 3.0 | HIGH |
|
1.8 | 5.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
— | CVE-2025-6663: 2 source package rows (gst-plugins-bad, gstreamer); 5 state rows across 4 repos (3.22-community, 3.22-main, edge-community, edge-main); fixed 2, open 3. | https://security.alpinelinux.org/vuln/CVE-2025-6663 |
debian
|
unimportant | CVE-2025-6663 unimportant priority: Debian including 1 source packages (gst-plugins-bad1.0), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. | https://security-tracker.debian.org/tracker/CVE-2025-6663 |
redhat
|
high | — | https://access.redhat.com/security/cve/CVE-2025-6663 |
ubuntu
|
medium | CVE-2025-6663 medium priority: Ubuntu including 1 source packages (gst-plugins-bad1.0), 10 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 6, ignored 2, not-affected 1, released 1. | https://ubuntu.com/security/CVE-2025-6663 |