CVE-2026-77639: 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…

PriorityP430medium5.3CVSS 3.1

AVNACLPRNUINSUCNINAL

EPSS

0.39%

32.0th percentile

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

2 ranges

Vendor	Product	Version range	Fixed in
torproject	tor	< 0.4.9.9	0.4.9.9
torproject	tor	>= 0.3.1.1-alpha < 0.4.9.9	0.4.9.9

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