CVE-2006-3409: Integer overflow in Tor before 0.1.1.20 allows remote attackers to execute arbitrary code via crafted large in

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HIGH 7.5DOWNGRADE

CVE-2006-3409 is a high-severity flaw (CVSS 7.5) affecting tor. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Integer overflow in Tor before 0.1.1.20 allows remote attackers to execute arbitrary code via crafted large inputs, which result in a buffer overflow when elements are added to smartlists.

Why this priority

High severity

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

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	3.7% (top 10%)
CISA exploited list	No
Published	2006-07-07
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

2006-07-07 00:05 UTCPublished CVE record published
2026-06-16 22:27 UTCUpdated Record last modified

tor tor DOWNGRADE

Affected: 0.0.2 · 0.0.2_pre13 · 0.0.2_pre14 · 0.0.2_pre15 · 0.0.2_pre16 · 0.0.2_pre17 · 0.0.2_pre18 · 0.0.2_pre19

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.0.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.0.2 (Debian / Ubuntu)

apt-cache madison tor sudo apt install tor=<VERSION_BEFORE_0.0.2> sudo apt-mark hold tor

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

dnf --showduplicates list tor sudo dnf downgrade tor-<VERSION_BEFORE_0.0.2> 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-2006-3409?

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

Is CVE-2006-3409 being exploited?

CVE-2006-3409 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-2006-3409 affect?

CVE-2006-3409 affects tor. Severity is high (CVSS 7.5). Integer overflow in Tor before 0.1.1.20 allows remote attackers to execute arbitrary code via crafted large inputs, which result in a buffer overflow when elements are added to smartlists.

How urgent is CVE-2006-3409?

Priority 49/100. High severity

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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