What is CVE-2025-67726?

CVE-2025-67726 is a high-severity vulnerability in Tornadoweb Tornado, classified under Excessive Iteration. CVSS score: 7.5/10. Published 2025-12-12.

How severe is CVE-2025-67726?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Tornadoweb Tornado

CVE-2025-67726

Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient algorithm when parsing parameters for HTTP header values, potentially causing a DoS. The _parseparam function in httputil.py…

EPSS: 0.000 (11.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Tornadoweb Tornado — versions < 6.5.3

Weakness classification (CWE)

References

https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8 (x_refsource_CONFIRM)
https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd (x_refsource_MISC)
https://github.com/tornadoweb/tornado/releases/tag/v6.5.3 (x_refsource_MISC)

Frequently asked questions

What is CVE-2025-67726?: CVE-2025-67726 is a high-severity vulnerability in Tornadoweb Tornado, classified under Excessive Iteration. CVSS score: 7.5/10. Published 2025-12-12.
How severe is CVE-2025-67726?: High severity. CVSS v3 base score is 7.5 out of 10.