PatchTheCVECVE-2026-77584: Tor before 0.4.9.10 did not reject a CONFLUX_LINK cell that arrives on a circuit which already has attached st
CVE-2026-77584 is a high-severity flaw (CVSS 7.0) affecting tor. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Tor 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 RELAY_COMMAND_BEGIN before the CONFLUX_LINK on the same circuit, attaching an exit stream that would later end up orphan leaving a dangling circuit back-pointer and a use-after-free (UAF) when the circuit is freed. This is TROVE-2026-025.
Why this priority
- High severity
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.0 (High) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.2% (top 84%) |
| CISA exploited list | No |
| Weakness | CWE-821 |
| Published | 2026-08-20 |
| Last modified | 2026-10-18 |
Last updated 2026-10-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-77584?
tor: upgrade to 0.4.9.10. Exact commands for each OS are on this page.
Is CVE-2026-77584 being exploited?
CVE-2026-77584 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-77584 affect?
CVE-2026-77584 affects tor. Severity is high (CVSS 7.0). Tor 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 RELAY_COMMAND_BEGIN before the CONFLUX_LINK on the same circuit, attaching an exit stream t
How urgent is CVE-2026-77584?
Priority 34/100. High severity; Remotely exploitable, no login, no user action
Related CVEs
- CVE-2026-44603 LOW 3.7 UPGRADE Tor before 0.4.9.7 has an out-of-bounds read by one byte via a malformed BEGIN cell, aka TROVE-2026-007.
- CVE-2026-44597 LOW 3.7 UPGRADE Tor before 0.4.9.7 has an out-of-bounds read when an END, a TRUNCATE, or a TRUNCATED cell lacks a reason in it
- CVE-2026-44600 LOW 3.7 UPGRADE Tor before 0.4.9.7 mishandles accounting of the conflux out-of-order queue during the clearing of a queue, aka
- CVE-2026-44601 LOW 3.7 UPGRADE Tor before 0.4.9.7, when circuit queue memory pressure exists, can experience a client crash because of a doub
- CVE-2026-44602 LOW 3.7 UPGRADE Tor before 0.4.9.7 has a NULL pointer dereference when a CERT cell is received out of order, aka TROVE-2026-00