FFmpeg versions from 0.5 up to, but not including, 9.0 contain an uninitialized heap memory disclosure vulnerability in the native TIFF decoder in… (CVE-2026-70631)
FFmpeg versions from 0.5 up to, but not including, 9.0 contain an uninitialized heap memory disclosure vulnerability in the native TIFF decoder in libavcodec/tiff.c. An attacker who can cause FFmpeg to decode a crafted TIFF file can supply a valid Deflate-compressed strip that terminates successfully after producing fewer bytes than the declared strip requires. The tiff_unpack_zlib() function allocates a heap buffer sized for the full declared strip but copies all declared rows via memcpy() regardless of how many bytes zlib actually decompressed, causing unwritten bytes that can contain stale data from prior heap allocations to be incorporated into decoded image output and potentially exposing sensitive data in persistent services.
AI Analysis
Technical Summary
The vulnerability (CVE-2026-70631) exists in FFmpeg's native TIFF decoder (libavcodec/tiff.c) in versions >=0.5 and <9.0. When decoding a crafted TIFF file, if a Deflate-compressed strip decompresses fewer bytes than declared, the tiff_unpack_zlib() function allocates a heap buffer for the full strip size but copies all declared rows regardless of decompressed byte count. This results in uninitialized heap memory being included in the decoded image output, potentially disclosing sensitive data from prior heap allocations. The flaw is classified under CWE-908 (Use of Uninitialized Resource).
Potential Impact
An attacker able to supply a crafted TIFF file to FFmpeg can cause disclosure of uninitialized heap memory contents. This may expose sensitive data in persistent services that use the vulnerable TIFF decoder. The vulnerability does not affect integrity or availability, only confidentiality, and requires local or limited access (AV:L) with user interaction (UI:R).
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor FFmpeg vendor advisories for updates addressing this vulnerability.
FFmpeg versions from 0.5 up to, but not including, 9.0 contain an uninitialized heap memory disclosure vulnerability in the native TIFF decoder in… (CVE-2026-70631)
Description
FFmpeg versions from 0.5 up to, but not including, 9.0 contain an uninitialized heap memory disclosure vulnerability in the native TIFF decoder in libavcodec/tiff.c. An attacker who can cause FFmpeg to decode a crafted TIFF file can supply a valid Deflate-compressed strip that terminates successfully after producing fewer bytes than the declared strip requires. The tiff_unpack_zlib() function allocates a heap buffer sized for the full declared strip but copies all declared rows via memcpy() regardless of how many bytes zlib actually decompressed, causing unwritten bytes that can contain stale data from prior heap allocations to be incorporated into decoded image output and potentially exposing sensitive data in persistent services.
CVSS v3.1
Score 5.5medium
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability (CVE-2026-70631) exists in FFmpeg's native TIFF decoder (libavcodec/tiff.c) in versions >=0.5 and <9.0. When decoding a crafted TIFF file, if a Deflate-compressed strip decompresses fewer bytes than declared, the tiff_unpack_zlib() function allocates a heap buffer for the full strip size but copies all declared rows regardless of decompressed byte count. This results in uninitialized heap memory being included in the decoded image output, potentially disclosing sensitive data from prior heap allocations. The flaw is classified under CWE-908 (Use of Uninitialized Resource).
Potential Impact
An attacker able to supply a crafted TIFF file to FFmpeg can cause disclosure of uninitialized heap memory contents. This may expose sensitive data in persistent services that use the vulnerable TIFF decoder. The vulnerability does not affect integrity or availability, only confidentiality, and requires local or limited access (AV:L) with user interaction (UI:R).
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor FFmpeg vendor advisories for updates addressing this vulnerability.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-5f73-3r3j-p8mr
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-70631"]
- Ecosystems
- []
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6a75739bbf8831d539d91c3b
Added to database: 08/07/2026, 05:56:43 UTC
Last enriched: 08/07/2026, 08:47:59 UTC
Last updated: 08/08/2026, 00:41:15 UTC
Views: 2
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.