CVE-2026-77639

EUVD-2026-63648
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: 30.82%
Affected Products (NVD)
VendorProductVersion
torprojecttor
𝑥
< 0.4.9.9
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
tor
bookworm
0.4.9.11-0+deb12u1
fixed
bookworm (security)
0.4.9.11-0+deb12u1
fixed
forky
0.4.9.12-4
fixed
sid
0.4.9.13-1
fixed
trixie
0.4.9.11-0+deb13u1
fixed
trixie (security)
0.4.9.13-0+deb13u1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
tor
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
trusty
needs-triage
xenial
needs-triage
Common Weakness Enumeration
References
https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog