How severe is CVE-2021-34548?

CVE-2021-34548 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-34548 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34548?

CVE-2021-34548 affects Torproject Tor. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-34548?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-34548 published?

CVE-2021-34548 was published on 2021-06-29 and last updated on 2026-06-17.

CVE-2021-34548

CVE-2021-34548 is a high-severity vulnerability in Torproject Tor with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-290.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-290
Affected product: Torproject Tor
Published: 2021-06-29
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-34548?: 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.
How severe is CVE-2021-34548?: CVE-2021-34548 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-34548 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34548?: CVE-2021-34548 affects Torproject Tor. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-34548?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-34548 published?: CVE-2021-34548 was published on 2021-06-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*

More vulnerabilities in Torproject Tor

CVE-2022-33903 — High (CVSS 7.5): Tor 0.4.7.x before 0.4.7.8 allows a denial of service via the wedging of RTT estimation.
CVE-2021-38385 — High (CVSS 7.5): Tor before 0.3.5.16, 0.4.5.10, and 0.4.6.7 mishandles the relationship between batch-signature verification and…
CVE-2021-34550 — High (CVSS 7.5): An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows…
CVE-2021-34549 — High (CVSS 7.5): An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-005. Hashing is mishandled for certain retrieval of…
CVE-2021-28089 — High (CVSS 7.5): Tor before 0.4.5.7 allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target, aka…
CVE-2020-15572 — High (CVSS 7.5): Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor…

All CVEs affecting Torproject Tor →

Other CWE-290 vulnerabilities

CVE-2026-48567 — Critical (CVSS 10.0): Authentication bypass by spoofing in Azure HorizonDB allows an unauthorized attacker to elevate privileges over a…
CVE-2026-6213 — Critical (CVSS 10.0): A vulnerability in Remote Spark SparkView before build 1122 allows an attacker to bypasses the local connection check…
CVE-2026-39858 — Critical (CVSS 10.0): Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a high…
CVE-2025-66570 — Critical (CVSS 10.0): cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.27.0, a vulnerability…
CVE-2025-34063 — Critical (CVSS 10.0): A cryptographic authentication bypass vulnerability exists in OneLogin AD Connector prior to 6.1.5 due to the exposure…
CVE-2023-22814 — Critical (CVSS 10.0): An authentication bypass issue via spoofing was discovered in the token-based authentication mechanism that could allow…

Browse all CWE-290 vulnerabilities →