Buffer overflow in Torproject Tor
CVE-2026-77642
tor before 0.4.9.9 was prone to an out-of-bounds write when parsing a consensus or detached signature with unexpected signature digest type. Impact is minor for most Tor roles, but potentially major for directory authorities. This is TROVE-2026-019.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.004 (26.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 26.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.002
Affected products
Weakness classification (CWE)
References
- gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog (Permissions Required, Release Notes, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-77642?
- CVE-2026-77642 is a high-severity vulnerability in Torproject Tor, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2026-08-20.
- How severe is CVE-2026-77642?
- High severity. CVSS v3 base score is 7.5 out of 10.