CVE-2021-3733
What it is
There's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client (such as web browser) connects to, could trigger a Regular Expression Denial of Service (ReDOS) during an authentication request with a specially crafted payload that is sent by the server to the client. The greatest threat that this flaw poses is to application availability.
At a glance
- Exploitability
- Can be exploited over the network with a low-privilege account. High risk of service disruption.
- Exploit odds
- 4.8% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 4.8% in the next 30 days (EPSS).
- Severity: 6.5 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 4.8% · EPSS, next 30 days
- Weakness
- CWE-400 · Uncontrolled resource consumption
- Record status
- Modified
Affected
- Python < 3.6.14
- Python < 3.7.11
- Python < 3.8.10
- Python < 3.9.5
- Python 3.10.0
- Redhat Codeready Linux Builder 8.0
- Redhat Codeready Linux Builder For IBM Z Systems 8.0
- Redhat Codeready Linux Builder For Power Little Endian 8.0
Attack profile CVSS 3.1 · 6.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-3733.md and follow it. Check whether this project is affected by CVE-2021-3733. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://bugs.python.org/issue43075
- https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb
- https://github.com/python/cpython/pull/24391
- https://ubuntu.com/security/CVE-2021-3733
- https://bugs.python.org/issue43075
- https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb
- https://github.com/python/cpython/pull/24391
- https://ubuntu.com/security/CVE-2021-3733
References
- https://bugs.python.org/issue43075
- https://bugzilla.redhat.com/show_bug.cgi?id=1995234
- https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb
- https://github.com/python/cpython/pull/24391
- https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
- https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
- https://security.netapp.com/advisory/ntap-20220407-0001/
- https://ubuntu.com/security/CVE-2021-3733
- https://bugs.python.org/issue43075
- https://bugzilla.redhat.com/show_bug.cgi?id=1995234
- https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb
- https://github.com/python/cpython/pull/24391
- https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
- https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
- https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html
- https://security.netapp.com/advisory/ntap-20220407-0001/
- https://ubuntu.com/security/CVE-2021-3733
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html