CVE-2025-67726

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Source
https://cve.org/CVERecord?id=CVE-2025-67726
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-67726.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2025-67726
Aliases
Downstream
BELL (1)
CLSA (1)
DEBIAN (1)
ECHO (1)
MGASA (1)
MINI (2)
OESA (2)
openSUSE (4)
RHSA (5)
RLSA (1)
SUSE (28)
UBUNTU (1)
Related
ALSA (1)
openSUSE (4)
SUSE (28)
Published
2025-12-12T06:13:51Z
Modified
2026-10-21T02:30:59Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
Tornado is Vulnerable to Quadratic DoS via Crafted Multipart Parameters
Details

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 is used to parse specific HTTP header values, such as those in multipart/form-data and repeatedly calls string.count() within a nested loop while processing quoted semicolons. If an attacker sends a request with a large number of maliciously crafted parameters in a Content-Disposition header, the server's CPU usage increases quadratically (O(n²)) during parsing. Due to Tornado's single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period. This issue is fixed in version 6.5.3.

Database specific 
{
    "cna_assigner":  "GitHub_M",
    "cwe_ids":  [
        "CWE-400",
        "CWE-834"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/67xxx/CVE-2025-67726.json"
}
References

Affected packages

Git / github.com/tornadoweb/tornado

Affected ranges

Type
GIT
Repo
https://github.com/tornadoweb/tornado
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
38014ddb51520ff7762c1d55535925dba2cdbe31
Fixed
771472cfdaeebc0d89a9cc46e249f8891a6b29cd
Database specific
Show details 
{
    "extracted_events":  [
        {
            "cpe":  "cpe:2.3:a:tornadoweb:tornado:*:*:*:*:*:*:*:*",
            "range":  [
                {
                    "introduced":  "0"
                },
                {
                    "fixed":  "6.5.3"
                }
            ],
            "source":  "CPE_RANGE"
        },
        {
            "range":  [
                {
                    "fixed":  "771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
                }
            ],
            "source":  "REFERENCES_COMMIT"
        },
        {
            "original_tag":  "v6.5.3",
            "range":  [
                {
                    "fixed":  "38014ddb51520ff7762c1d55535925dba2cdbe31"
                }
            ],
            "source":  "REFERENCES_TAG"
        }
    ]
}

Affected versions

v1.*
v1.0.0
v1.1.0
v1.2.0
v2.*
v2.0.0
v2.1.0
v2.1.1
v2.2.0
v2.3.0
v3.*
v3.0.0
v3.0.1
v3.1.0
v3.2.0
v3.2.0b1
v3.2.0b2
v4.*
v4.0.0
v4.0.0b1
v4.0.0b2
v4.0.0b3
v4.1.0
v4.1.0b1
v4.1.0b2
v4.2.0
v4.2.0b1
v4.3.0
v4.3.0b1
v4.3.0b2
v4.4.0
v4.4.0b1
v4.4.1
v4.5.0
v4.5.1
v5.*
v5.0.0
v5.1.0
v6.*
v6.0.0
v6.0.0b1
v6.1.0
v6.1.0b1
v6.1.0b2
v6.2.0
v6.2.0b1
v6.2.0b2
v6.3.0
v6.3.0b1
v6.3.1
v6.4.0
v6.4.0b1
v6.4.1
v6.5.0
v6.5.0b1
v6.5.1
v6.5.2

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-67726.json"