CVE-2020-5236

NameCVE-2020-5236
DescriptionWaitress version 1.4.2 allows a DOS attack When waitress receives a header that contains invalid characters. When a header like "Bad-header: xxxxxxxxxxxxxxx\x10" is received, it will cause the regular expression engine to catastrophically backtrack causing the process to use 100% CPU time and blocking any other interactions. This allows an attacker to send a single request with an invalid header and take the service offline. This issue was introduced in version 1.4.2 when the regular expression was updated to attempt to match the behaviour required by errata associated with RFC7230. The regular expression that is used to validate incoming headers has been updated in version 1.4.3, it is recommended that people upgrade to the new version of Waitress as soon as possible.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
waitress (PTS)stretch1.0.1-1fixed
buster1.2.0~b2-2fixed
bullseye, sid1.4.1-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
waitresssource(unstable)(not affected)

Notes

- waitress <not-affected> (Vulnerable code introduced later)
https://github.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc
Introduced in: https://github.com/Pylons/waitress/commit/0bf98dadd8cae23830cb365cc6cb9cedd7f98db0 (v1.4.2)
https://github.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f (v1.4.3)

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