Heap Buffer Overflow in FFmpeg via DVB Subtitle Parser

Publication date: 2026-08-06

Last updated on: 2026-08-06

Assigner: VulnCheck

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-06

Last Modified

2026-08-06

Generated

2026-08-07

AI Q&A

2026-08-07

EPSS Evaluated

N/A

NVD

CVE-2026-70628

Affected Vendors & Products

Vendor	Product	Version / Range
ffmpeg	ffmpeg	From 0.5 (inc) to 9.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-787	The product writes data past the end, or before the beginning, of the intended buffer.
CWE-190	The product 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 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 become a very small or negative number.

Attack-Flow Graph

Executive Summary

This vulnerability is a signed integer overflow in FFmpeg versions 0.5 to 9.0. It occurs in the DVB subtitle parser where a crafted WTV file can cause an overflow. This bypasses bounds checks, leading to a heap buffer overflow via memcpy with attacker-controlled data, potentially causing memory corruption or code execution.

Impact Analysis

If exploited, this vulnerability could allow attackers to execute arbitrary code or cause denial-of-service conditions on systems processing malicious WTV files. Local attackers with access to vulnerable FFmpeg versions may gain elevated privileges or crash applications.

Mitigation Strategies

Update FFmpeg to version 9.0 or later to address the signed integer overflow in the DVB subtitle parser. Avoid processing untrusted WTV files until patched.

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