PYSEC-2026-1974

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Import Source

https://github.com/pypa/advisory-database/blob/main/vulns/tornado/PYSEC-2026-1974.yaml

JSON Data

https://api.test.osv.dev/v1/vulns/PYSEC-2026-1974

Aliases

Published

2026-07-07T16:02:52.554242Z

Modified

2026-07-07T17:48:06.813205040Z

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 vulnerable to excessive logging caused by malformed multipart form data

Details

Summary

When Tornado's multipart/form-data parser encounters certain errors, it logs a warning but continues trying to parse the remainder of the data. This allows remote attackers to generate an extremely high volume of logs, constituting a DoS attack. This DoS is compounded by the fact that the logging subsystem is synchronous.

Affected versions

All versions of Tornado prior to 6.5 are affected. The vulnerable parser is enabled by default.

Solution

Upgrade to Tornado version 6.5. In the meantime, risk can be mitigated by blocking Content-Type: multipart/form-data in a proxy.

References

Affected packages

PyPI / tornado

Package

Name: tornado; View open source insights on deps.dev
Purl: pkg:pypi/tornado

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

6.5

Affected versions

0.*

0.2

1.*

1.0

1.1

1.1.1

1.2

1.2.1

2.*

2.0

2.1

2.1.1

2.2

2.2.1

2.3

2.4

2.4.1

3.*

3.0

3.0.1

3.0.2

3.1

3.1.1

3.2

3.2.1

3.2.2

4.*

4.0

4.0.1

4.0.2

4.1b2

4.1

4.2b1

4.2

4.2.1

4.3b1

4.3b2

4.3

4.4b1

4.4

4.4.1

4.4.2

4.4.3

4.5b1

4.5b2

4.5

4.5.1

4.5.2

4.5.3

5.*

5.0a1

5.0b1

5.0

5.0.1

5.0.2

5.1b1

5.1

5.1.1

6.*

6.0a1

6.0b1

6.0

6.0.1

6.0.2

6.0.3

6.0.4

6.1b1

6.1b2

6.1

6.2b1

6.2b2

6.2

6.3b1

6.3

6.3.1

6.3.2

6.3.3

6.4b1

6.4

6.4.1

6.4.2

6.5b1

Database specific

source

"https://github.com/pypa/advisory-database/blob/main/vulns/tornado/PYSEC-2026-1974.yaml"