CVE-2021-34548

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-06-29 · updated 2026-06-17
Weakness: CWE-290

Description

An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-003. An attacker can forge RELAY_END or RELAY_RESOLVED to bypass the intended access control for ending a stream.

Affected products

torproject Tor: before 0.3.5.15; from 0.4.0.0 before 0.4.4.9; from 0.4.5.0 before 0.4.5.9; from 0.4.6.0 before 0.4.6.5 — fixed in 0.3.5.15, 0.4.4.9, 0.4.5.9, 0.4.6.5

How to fix

Upgrade to a fixed version: torproject Tor 0.3.5.15, 0.4.4.9, 0.4.5.9, 0.4.6.5. Check the vendor advisory for mitigations.

References

http://packetstormsecurity.com/files/163510/Tor-Half-Closed-Connection-Stream-Confusion.html
https://blog.torproject.org/node/2041
https://gitlab.torproject.org/tpo/core/tor/-/issues/40389
https://security.gentoo.org/glsa/202107-25
http://packetstormsecurity.com/files/163510/Tor-Half-Closed-Connection-Stream-Confusion.html
https://blog.torproject.org/node/2041
https://gitlab.torproject.org/tpo/core/tor/-/issues/40389
https://security.gentoo.org/glsa/202107-25

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