Description
Tor before 0.4.9.9 was prone to a compression bomb bypass where an attacker could concatenate many gzip or zlib sub-streams, each just under the per-stream detection threshold, to avoid the compression bomb check entirely. This is TROVE-2026-022.
Affected products
torproject: tor
References1
- gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog Release NotesVendor Advisory
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - EPSS — exploit probability
- 0% percentile: 34 · as of 10 November 2026
- CWE
- CWE-420
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.