{"id":"CVE-2026-77639","title":"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","summary":"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-…","severity":"medium","cvss":5.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","cwe":["CWE-420"],"vendor":"torproject","product":"tor","affected":["tor < 0.4.9.9"],"patched":["tor 0.4.9.9"],"published":"2026-08-20","updated":"2026-09-08","sourceUpdated":"2026-09-08T18:33:36.520","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-77639","references":[{"url":"https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog","label":"cve@mitre.org"}],"tags":["nvd"],"epss":0.00231,"epssPercentile":0.14189,"ingestedAt":"2026-09-08T19:08:49.591Z","slug":"CVE-2026-77639","body":"## Overview\n\nTor 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.\n\n## Affected\n\n- `tor < 0.4.9.9`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `tor 0.4.9.9`","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}