Signed int overflow in FFmpeg DVB subtitle parser (v<9.0)
CVE-2026-70628 Published on August 6, 2026
FFmpeg 0.5 < 9.0 DVB Subtitle Parser Heap Buffer Overflow via WTV File
FFmpeg versions from 0.5 up to, but not including, 9.0 contain a signed integer overflow vulnerability in the DVB subtitle parser in libavcodec/dvbsub_parser.c that allows attackers to trigger a heap buffer overflow by supplying a crafted WTV file. The overflow causes the bounds-check guard expression to wrap to INT_MIN, bypassing the PARSE_BUF_SIZE comparison and invoking memcpy() with attacker-controlled data into a heap buffer, resulting in an out-of-bounds heap write and potential memory corruption or code execution.
Vulnerability Analysis
CVE-2026-70628 is exploitable with local system access. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Types
Integer Overflow or Wraparound
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. An integer overflow or wraparound occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may wrap to become a very small or negative number. While this may be intended behavior in circumstances that rely on wrapping, it can have security consequences if the wrap is unexpected. This is especially the case if the integer overflow can be triggered using user-supplied inputs. This becomes security-critical when the result is used to control looping, make a security decision, or determine the offset or size in behaviors such as memory allocation, copying, concatenation, etc.
What is a Memory Corruption Vulnerability?
The software writes data past the end, or before the beginning, of the intended buffer. Typically, this can result in corruption of data, a crash, or code execution. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent write operation then produces undefined or unexpected results.
CVE-2026-70628 has been classified to as a Memory Corruption vulnerability or weakness.
Products Associated with CVE-2026-70628
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Affected Versions
FFmpeg:- Version 0.5 and below 9.0 is affected.