CVE-2024-49767

Werkzeug is a Web Server Gateway Interface web application library. Applications using werkzeug.formparser.MultiPartParser corresponding to a version of Werkzeug prior to 3.0.6 to parse multipart/form-data requests (e.g. all flask applications) are vulnerable to a relatively simple but effective resource exhaustion (denial of service) attack. A specifically crafted form submission request can cause the parser to allocate and block 3 to 8 times the upload size in main memory. There is no upper limit; a single upload at 1 Gbit/s can exhaust 32 GB of RAM in less than 60 seconds. Werkzeug version 3.0.6 fixes this issue.

Weakness

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• https://github.com/pallets/quart/commit/5e78c4169b8eb66b91ead3e62d44721b9e1644ee
• https://github.com/pallets/quart/commit/abb04a512496206de279225340ed022852fbf51f
• https://github.com/pallets/werkzeug/commit/50cfeebcb0727e18cc52ffbeb125f4a66551179b
• https://github.com/pallets/werkzeug/releases/tag/3.0.6
• https://github.com/pallets/werkzeug/security/advisories/GHSA-q34m-jh98-gwm2
• https://security.netapp.com/advisory/ntap-20250103-0007/