Bug 2516042

Summary: CVE-2026-70631 ffmpeg: FFmpeg: Information disclosure via uninitialized heap memory read in TIFF decoder [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Joel Chamberlain <jochambe>
Component: ffmpegAssignee: Multimedia SIG <multimedia-sig>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: epel10CC: asn, dominik, multimedia-sig, ngompa13, philip.wyett
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["14d406f6-9cb6-4328-a7ac-de96199b11a4"]}
Fixed In Version: Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2512210    

Description Joel Chamberlain 2026-08-14 14:34:31 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.