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Fencer Vulns
medium 6.5

CVE-2026-87724 json

Tor before 0.4.9.12 interprets the CC_RESPONSE extension even when CC_REQUEST was not sent, which allows remote attackers to cause a denial…

published 2026-09-09 2 mo ago modified 2026-09-09 1 mo ago also EUVD-2026-74539

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

Tor before 0.4.9.12 interprets the CC_RESPONSE extension even when CC_REQUEST was not sent, which allows remote attackers to cause a denial of service (crash) because of corrupted congestion-control state. This is TROVE-2026-032.

Patch / fix

  • torprject Tor 0.4.9.12
  • tor Debian 13 0.4.9.12-0+deb13u2
  • tor Debian 14 0.4.9.12-2

debian advisories DEBIAN-CVE-2026-87724

  • tor openSUSE Tumbleweed 0.4.9.13-1.1

opensuse advisories openSUSE-SU-2026:11909-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-87724 updated cvss 6.5

Tor: Tor: Denial of Service via misinterpretation of congestion-control extension

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
1 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected products

  • torprject Tor

Classification

Weakness
  • CWE-669 Incorrect Resource Transfer Between Spheres

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.