Submit #913780: GPAC up to commit f1219cde (2026-07-25) Denial of Service

A vulnerability was found in GPAC up to commit f1219cde (2026-07-25) and classified as problematic. Affected is the scene graph node handling related to instance counting in the component MP4Box. The manipulation via a crafted MP4 file processed with the -nstatx argument leads to a reachable assertion failure (assert(num_instances)) that causes an immediate process abort. It is possible to launch the attack locally. User interaction is required.

Technical Details
- Affected file/function: scenegraph/base_scenegraph.c:753 / gf_node_unregister
- Vulnerable parameter: Malformed ISO data (corrupted stts, unknown/incomplete boxes) leading to corrupted node instance tracking
- Attack vector: Local
- Privileges required: None
- Trigger condition: Processing a crafted MP4 file with "MP4Box -nstatx" causes malformed ISO parsing that corrupts scene graph node state. A node's instance counter reaches zero, but is still accessed during scene analysis, triggering assert(pNode->sgprivate->num_instances) at base_scenegraph.c:753. Requires --enable-debug build.

Impact
- Confidentiality: None
- Integrity: None
- Availability: High

CVSS v3.1
Score: 5.5 (Medium)
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Timeline
- Discovered: 2026-07-27
- Vendor notified: 2026-07-27
- Patch released: 2026-07-28
- Public disclosure: 2026-07-27

Countermeasure
Apply the upstream patch. Replace the reachable assertion with proper error handling that checks node instance count before access.

• Quelle: ⚠️ https://github.com/r1ck9-2q/cve_summit/blob/main/Vuln%20GPAC%20MP4Box%20Assertion%20Failure%20assert(num_instances).md
• Benutzer: r1ck9 (UID 97869)
• Einreichung: 03.08.2026 07:19 (vor 2 Monaten)
• Moderieren: 13.09.2026 06:55 (1 month later)
• Status: Akzeptiert
• VulDB Eintrag: 403216 [GPAC bis f1219cde MP4Box base_scenegraph.c gf_node_unregister Denial of Service]
• Punkte: 20