CVE-2026-77639

Published: August 20th, 2026
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.
MEDIUM
CVSS v3: 5.3

Status

DocFilters Release Package State Justification Comment
26.3 zlib (1.3) Needs Triage
26.2 zlib (1.3) Needs Triage
26.1 zlib (1.3) Needs Triage
25.4 zlib (1.3) Needs Triage
25.3 zlib (1.3) Needs Triage
25.2 zlib (1.3) Needs Triage
25.1 zlib (1.3) Needs Triage
24.4 zlib (1.3) Needs Triage
24.4.0 zlib (1.3) Needs Triage
24.3 zlib (1.3) Needs Triage
24.2 zlib (1.3) Needs Triage
24.1 zlib (1.3) Needs Triage
23.3 zlib (1.3) Needs Triage
23.2 zlib (1.2.12) Needs Triage
23.1 zlib (1.2.12) Needs Triage
22.4 zlib (1.2.12) Needs Triage
22.3 zlib (1.2.12) Needs Triage
22.2 zlib (1.2.12) Needs Triage
22.1 zlib (1.2.11) Needs Triage
21.11 zlib (1.2.11) Needs Triage
21.8 zlib (1.2.11) Needs Triage
21.5.0 zlib (1.2.11) Needs Triage
21.2.0 zlib (1.2.11) Needs Triage
11.4.19.3667 zlib (1.2.11) Needs Triage
11.4.18.3599 zlib (1.2.11) Needs Triage
11.4.16.3445 zlib (1.2.11) Needs Triage
11.4.15.3368 zlib (1.2.11) Needs Triage
11.4.14.3263 zlib (1.2.11) Needs Triage
11.4.13.3179 zlib (1.2.11) Needs Triage
11.4.12.3054 zlib (1.2.11) Needs Triage
11.4.11.3040 zlib (1.2.11) Needs Triage
11.4.11.2990 zlib (1.2.11) Needs Triage
11.4.10.2934 zlib (1.2.11) Needs Triage
11.4.9.2878 zlib (1.2.11) Needs Triage
11.4.8.2822 zlib (1.2.11) Needs Triage

Severity score breakdown

Attack Complexity
LOW
Attack Vector
NETWORK
Availability Impact
LOW
Base Score
5.3
Base Severity
MEDIUM
Confidentiality Impact
NONE
Integrity Impact
NONE
Privileges Required
NONE
Scope
UNCHANGED
User Interaction
NONE
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Version
3.1

References