How severe is CVE-2018-0491?

CVE-2018-0491 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-2018-0491 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-0491?

CVE-2018-0491 affects Torproject Tor. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-0491?

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-2018-0491 published?

CVE-2018-0491 was published on 2018-03-05 and last updated on 2026-06-17.

CVE-2018-0491

CVE-2018-0491 is a high-severity vulnerability in Torproject Tor with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 16% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-416.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 16% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Torproject Tor
Published: 2018-03-05
Last modified: 2026-06-17

Description

A use-after-free issue was discovered in Tor 0.3.2.x before 0.3.2.10. It allows remote attackers to cause a denial of service (relay crash) because the KIST implementation allows a channel to be added more than once in the pending list.

Frequently asked questions

What is CVE-2018-0491?: A use-after-free issue was discovered in Tor 0.3.2.x before 0.3.2.10. It allows remote attackers to cause a denial of service (relay crash) because the KIST implementation allows a channel to be added more than once in the pending list.
How severe is CVE-2018-0491?: CVE-2018-0491 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-2018-0491 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-0491?: CVE-2018-0491 affects Torproject Tor. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-0491?: 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-2018-0491 published?: CVE-2018-0491 was published on 2018-03-05 and last updated on 2026-06-17.

References

Affected products (1)

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

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