CVE-2026-77639
A remote anonymous attacker can exploit multiple vulnerabilities in Tor to bypass security measures, manipulate data, disclose information, or trigger a denial-of-service condition.
CSIRTS triage
- What
- Multiple vulnerabilities in Tor enable authentication bypass, data manipulation, information disclosure, and denial of service.
- Who is affected
- Tor relay and client deployments.
- Urgency
- High: severity rated high; authentication bypass in Tor impacts network security.
- Action
- Apply Tor security updates; check torproject.org for patched versions and release notes.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch CVE-2026-77639
Get an email if CVE-2026-77639 is added to CISA KEV, gains public exploit code, or a new advisory cites it — max one per day, one-click unsubscribe.
Exploitation outlook
- Low exploitation risk0.25% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 16% of all EPSS-scored CVEs.
Advisory coverage (2)
- high[NEW] [high] Tor: Multiple vulnerabilitiescert-bund · 2026-08-21
- mediumCVE-2026-77639: Tor before 0.4.9.9 was prone to a compression bomb bypass where an attacker could concatenate …nvd · 2026-08-20
External references
Embed the live status
— this badge updates automatically when the KEV or exploit status changes. How to embed it →
[](https://www.csirts.com/cve/CVE-2026-77639)