CVE-2007-4098: Tor before 0.1.2.15 does not properly distinguish "streamids from different exits," which might allow remote a

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MEDIUM 5.8DOWNGRADE

CVE-2007-4098 is a medium-severity flaw (CVSS 5.8) affecting tor. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Tor before 0.1.2.15 does not properly distinguish "streamids from different exits," which might allow remote attackers with control over Tor routers to inject cells into arbitrary streams.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.8 (Medium)
EPSS exploit chance	1.9% (top 20%)
CISA exploited list	No
Published	2007-07-30
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

2007-07-30 21:17 UTCPublished CVE record published
2026-06-16 22:43 UTCUpdated Record last modified

tor tor DOWNGRADE

Affected: 0.1.0.10 · 0.1.0.11 · 0.1.0.12 · 0.1.0.13 · 0.1.0.14 · 0.1.0.18 · 0.1.1.1_alpha · 0.1.1.2_alpha

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.1.0.10

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.1.0.10 (Debian / Ubuntu)

apt-cache madison tor sudo apt install tor=<VERSION_BEFORE_0.1.0.10> sudo apt-mark hold tor

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

dnf --showduplicates list tor sudo dnf downgrade tor-<VERSION_BEFORE_0.1.0.10> 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-2007-4098?

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

Is CVE-2007-4098 being exploited?

CVE-2007-4098 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-2007-4098 affect?

CVE-2007-4098 affects tor. Severity is medium (CVSS 5.8). Tor before 0.1.2.15 does not properly distinguish "streamids from different exits," which might allow remote attackers with control over Tor routers to inject cells into arbitrary streams.

How urgent is CVE-2007-4098?

Priority 40/100. No elevated risk signals yet.

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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