Bug 2520793 (CVE-2026-77640) - CVE-2026-77640 tor: Tor: Denial of Service via truncated zlib/gzip stream decompression
Summary: CVE-2026-77640 tor: Tor: Denial of Service via truncated zlib/gzip stream dec...
Keywords:
Status: NEW
Alias: CVE-2026-77640
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2521288 2521289
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-20 21:25 UTC by OSIDB Bzimport
Modified: 2026-08-22 11:47 UTC (History)
0 users

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)

Description OSIDB Bzimport 2026-08-20 21:25:59 UTC 
tor before 0.4.9.9 was prone to an infinite loop when decompressing a truncated zlib/gzip  stream with done=1. A truncated stream never reaches Z_STREAM_END,  causing zlib to return Z_BUF_ERROR with no input remaining, which  buf_add_compress() mistook for a full output buffer and retried forever. Fixed by returning TOR_COMPRESS_ERROR in that case so the caller can abort cleanly. This is TROVE-2026-021.
Note You need to log in before you can comment on or make changes to this bug.