CVE-2025-67725: Tornado · Quadratic DoS via Repeated Header Coalescing
Affects snakevizSource GCVE Database
Not known to be exploited · CVSS 7.5 High : upgrade to 2.2.2_3 soon.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.2.2_3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 12 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade snakeviz to 2.2.2_3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewsnakevizpkg:brew/snakevizOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available in Tornado version 2.2.2_3 that fixes this vulnerability. Users should upgrade to this version or later to remediate the issue. No other mitigation is indicated or required.
Description
CVE-2025-67725 is a high-severity Denial of Service (DoS) vulnerability in Tornado's HTTPHeaders.add method. The vulnerability arises from inefficient string concatenation when the same HTTP header is repeated, causing quadratic time complexity. This can block Tornado's single event loop, leading to service unavailability. The impact is more severe if the max_header_size setting is increased beyond the default 64KB. A fix is available in Tornado version 2.2.2_3.
References
- github.com/tornadoweb/tornado/security/advisories/GHSA-c98p-7wgm-6p64 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2025-67725 (opens in a new tab)
- github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd (opens in a new tab)
- github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2025-266.yaml (opens in a new tab)
- github.com/tornadoweb/tornado (opens in a new tab)
- github.com/tornadoweb/tornado/releases/tag/v6.5.3 (opens in a new tab)