CVE-2026-77584Network attack vectorHinoki check available

Memory corruption via CONFLUX_LINK on busy circuits

Published Aug 20, 2026 · Updated Aug 20, 2026

Use-after-free in conflux circuit handling in The Tor Project Tor before 0.4.9.10 allows remote attackers to corrupt memory via crafted cells. The flaw is in CONFLUX_LINK processing: Tor accepts a link cell on a circuit that already carries streams, then a preceding RELAY_COMMAND_BEGIN can leave the adopted exit stream orphaned with a dangling circuit back-pointer when the circuit is later freed. Reachability requires a malicious client that can speak the Tor relay protocol to the vulnerable service; public sources describe memory corruption on circuit teardown, but do not publish a demonstrated code-execution path.

CVSS severity7.0
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Use-after-free in conflux circuit handling in The Tor Project Tor before 0.4.9.10 allows remote attackers to corrupt memory via crafted cells. The flaw is in CONFLUX_LINK processing: Tor accepts a link cell on a circuit that already carries streams, then a preceding RELAY_COMMAND_BEGIN can leave the adopted exit stream orphaned with a dangling circuit back-pointer when the circuit is later freed. Reachability requires a malicious client that can speak the Tor relay protocol to the vulnerable service; public sources describe memory corruption on circuit teardown, but do not publish a demonstrated code-execution path.

The record

CVE
CVE-2026-77584
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
The Tor Project
Product
Tor
Classifications
CWE-821, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.4.8.1-alpha <0.4.9.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Tor Project · Torversion=0.4.8.1-alpha <0.4.9.10

Published CVSS scores

7.0MITRECVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-821Incorrect Synchronization
T1499.004Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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