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Vulnerability record · CVE-2026-77642 · published 20 August 2026

CVE-2026-77642: Torproject tor out-of-bounds write vulnerability

Torproject · Tor

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.

9.3 CVSS 3.1 Critical EPSS 0.35% · top 73.6% CWE-787 · Out-of-bounds write
9.3CVSS 3.1 base score
0.35%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References
8 Sep 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog Permissions RequiredRelease NotesVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.5CVE-2016-9079Firefox and Tor Browser SVG Animation use-after-freeA use-after-free flaw in SVG Animation affects Firefox before 50.0.2, Firefox ESR before 45.5.1, and Thunderbird before 45.5.1. Mozilla reports an ex…KEVEPSS 87%analysed9.1CVE-2026-44603Torproject tor vulnerabilityTor before 0.4.9.7 has an out-of-bounds read by one byte via a malformed BEGIN cell, aka TROVE-2026-007.EPSS 0.63%9.1CVE-2026-44597Torproject tor vulnerabilityTor before 0.4.9.7 has an out-of-bounds read when an END, a TRUNCATE, or a TRUNCATED cell lacks a reason in its payload, aka TROVE-2026-011.EPSS 0.63%9.0CVE-2026-77638Torproject tor race condition vulnerabilityTor before 0.4.9.11 is prone to a race condition where in just the right circumstances a rendezvous point could man-in-the-middle (impersonate) the o…EPSS 0.30%8.2CVE-2026-77641Torproject tor unchecked return value vulnerabilitytor before 0.4.9.9 was prone to a NULL write after free when sending a CONFLUX_SWITCH cell fails. The return value of relay_send_command_from_edge() …EPSS 0.35%8.2CVE-2026-77584Torproject tor vulnerabilityTor before 0.4.9.10 did not reject a CONFLUX_LINK cell that arrives on a circuit which already has attached streams. A malicious client could send a …EPSS 0.25%7.5CVE-2026-77587Torproject tor use after free vulnerabilityTor before 0.4.9.11 is prone to a use-after-free (and potential double free) of a conflux object when a recovery leg revives a conflux set whose last…EPSS 0.40%7.5CVE-2026-44601Torproject tor vulnerabilityTor before 0.4.9.7, when circuit queue memory pressure exists, can experience a client crash because of a double close of a circuit, aka TROVE-2026-0…EPSS 0.60%

Source: NIST National Vulnerability Database (record CVE-2026-77642), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.