CVE-2026-75143: ffmpeg Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-75143 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in ffmpeg. EPSS estimates a 0.70% chance of exploitation in the next 30 days, higher than 52.3% of scored vulnerabilities.

Timeline

1. 19-08-2026
   PublishedVulnerability first disclosed.
2. 21-08-2026
   Last modifiedVulnerability information updated.

Description

FFmpeg before commit 1c10bcc contains a heap buffer overflow in the RIST protocol reader (libavformat/librist.c). librist_read() ignored its size argument and copied the full received payload length into the caller-provided destination buffer, overflowing it when the payload exceeds the destination size. This is reachable via the async:rist:// URL scheme, where the async wrapper supplies a smaller buffer than the received payload. A remote RIST sender can trigger the overflow by sending a packet whose payload exceeds the caller buffer size.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().