CVE-2021-21240

Regular Expression Denial of Service in httplib2

httplib2 is a comprehensive HTTP client library for Python. In httplib2 before version 0.19.0, a malicious server which responds with long series of "\xa0" characters in the "www-authenticate" header may cause Denial of Service (CPU burn while parsing header) of the httplib2 client accessing said server. This is fixed in version 0.19.0 which contains a new implementation of auth headers parsing using the pyparsing library.

Affected

httplib2

CVSS v4.0 GitHub

7.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

CVSS v3.1 NVD

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v2.0 NVD

5.0 MEDIUMAV:N/AC:L/Au:N/C:N/I:N/A:P

EPSS

3.63% chance of exploitation in the next 30 days, 89th percentile

Published

2021-02-08

Updated

2024-08-03

Proof-of-concept exploits (1)

• advisories/GHSA-93xj-8mrv-444m

Security advisories

• httplib2/httplib2/pull/182
• httplib2/httplib2/security/advisories/GHSA-93xj-8mrv-444m
• https://pypi.org/project/httplib2

References

• CVE Record
• NVD entry