Vulnerability Details : CVE-2020-5236
Waitress 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.
Vulnerability category: Denial of service
Products affected by CVE-2020-5236
- cpe:2.3:a:agendaless:waitress:1.4.2:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2020-5236
0.08%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 31 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2020-5236
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
|---|---|---|---|---|---|---|
|
6.8
|
MEDIUM | AV:N/AC:L/Au:S/C:N/I:N/A:C |
8.0
|
6.9
|
NIST | |
|
6.5
|
MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
2.8
|
3.6
|
NIST | |
|
5.7
|
MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H |
2.1
|
3.6
|
GitHub, Inc. |
CWE ids for CVE-2020-5236
-
The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.Assigned by:
- nvd@nist.gov (Primary)
- security-advisories@github.com (Secondary)
References for CVE-2020-5236
-
https://github.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f
Merge pull request from GHSA-73m2-3pwg-5fgc · Pylons/waitress@6e46f9e · GitHubPatch;Third Party Advisory
-
https://github.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc
Catastrophic backtracking in regex allows Denial of Service · Advisory · Pylons/waitress · GitHubThird Party Advisory
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