Executive brief
ZLMediaKit is an open-source framework used for high-performance streaming of media like video and audio. A security flaw in how it handles specific video data (VP9) allows an attacker to send a specially crafted network packet that causes the system to read memory incorrectly. This can lead to immediate service crashes, resulting in a denial of service for all connected users.
Technical details
An out-of-bounds read (CWE-125) exists in the VP9 RTP payload parser within `ext-codec/VP9Rtp.cpp`. The `RTPPayloadVP9::parse` function processes flag bits from the first byte of a payload to determine which optional fields (such as PictureID or Layer Indices) are present. However, it fails to validate the `dataLength` before incrementing the data pointer and dereferencing it. A remote, unauthenticated attacker can send a 1-byte RTP packet with all flag bits set (0xFF), forcing the parser to read multiple bytes past the end of the allocated heap buffer. This can result in a denial of service (segmentation fault) or potential information disclosure if the out-of-bounds data is incorporated into forwarded media frames. The issue is resolved in commit 435dcbcbbf700fd63b2ca9eac6cef3b5ea75169d.
Affected products
- ZLMediaKit ZLMediaKit versions up to (excluding) commit 435dcbc
Timeline
- 2026-04-02: advisory: GitHub Security Advisory published
- 2026-04-06: disclosed: CVE-2026-35203 published
- 2026-03-29: patched: Fix commit 435dcbc merged into master