What is 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.
The record classifies CVE-2026-77642 under weakness class CWE-787. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 46 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 7.5 — HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H - EPSS (FIRST)
- 0.1% probability of exploitation in the next 30 days, higher than 9.4% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 4.1/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-08-20
Is CVE-2026-77642 being exploited?
It currently carries a trending score of 32 in the Threadlinqs vulnerability feed.
Affected products and versions
- torproject: Tor
How to fix CVE-2026-77642
No vendor patch reference has been recorded for CVE-2026-77642 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-77642
No threat campaign in the Threadlinqs corpus currently references CVE-2026-77642, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on .