CVE-2006-6893: Tor allows remote attackers to discover the IP address of a hidden service by accessing this service at a high

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MEDIUM 5.0DOWNGRADE

CVE-2006-6893 is a medium-severity flaw (CVSS 5.0) affecting tor. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Tor allows remote attackers to discover the IP address of a hidden service by accessing this service at a high rate, thereby changing the server's CPU temperature and consequently changing the pattern of time values visible through (1) ICMP timestamps, (2) TCP sequence numbers, and (3) TCP timestamps, a different vulnerability than CVE-2006-0414. NOTE: it could be argued that this is a laws-of-physics vulnerability that is a fundamental design li

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Published	2006-12-31
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: tor

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2006-12-31 05:00 UTCPublished CVE record published
2026-06-16 22:34 UTCUpdated Record last modified

tor tor DOWNGRADE

Affected: 0.1.1.26

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.1.1.26

1. Check installed version

apt-cache policy tor || rpm -q tor || tor --version

2. No fixed release: DOWNGRADE to a release before 0.1.1.26 (Debian / Ubuntu)

apt-cache madison tor sudo apt install tor=<VERSION_BEFORE_0.1.1.26> sudo apt-mark hold tor

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list tor sudo dnf downgrade tor-<VERSION_BEFORE_0.1.1.26> sudo dnf versionlock add tor

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
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-2006-6893?

tor: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2006-6893 being exploited?

CVE-2006-6893 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-2006-6893 affect?

CVE-2006-6893 affects tor. Severity is medium (CVSS 5.0). Tor allows remote attackers to discover the IP address of a hidden service by accessing this service at a high rate, thereby changing the server's CPU temperature and consequently changing the pattern of time values visible through (1) ICMP

How urgent is CVE-2006-6893?

Priority 44/100. Public exploit reference

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

References

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