CVE-2009-0939

CVE-2009-0939 is a critical-severity vulnerability in Tor with a CVSS 2.0 base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

Tor before 0.2.0.34 treats incomplete IPv4 addresses as valid, which has unknown impact and attack vectors related to "Spec conformance," as demonstrated using 192.168.0.

Frequently asked questions

What is CVE-2009-0939?
Tor before 0.2.0.34 treats incomplete IPv4 addresses as valid, which has unknown impact and attack vectors related to "Spec conformance," as demonstrated using 192.168.0.
How severe is CVE-2009-0939?
CVE-2009-0939 has a CVSS 2.0 base score of 10.0, rated critical severity.
Is CVE-2009-0939 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-0939?
CVE-2009-0939 primarily affects Tor. In total, 30 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-0939?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2009-0939 published?
CVE-2009-0939 was published on 2009-03-18 and last updated on 2026-06-16.

References

Affected products (30)

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