CVE-2021-3737
What it is
A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client script enter an infinite loop, consuming CPU time. The highest threat from this vulnerability is to system availability.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 13.2% chance of exploitation in the next 30 days (EPSS). Higher than most.
- 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: 13.2% in the next 30 days (EPSS).
- Severity: 7.5 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 13.2% · EPSS, next 30 days
- Weakness
- CWE-835
- Record status
- Modified
Affected
- Python < 3.6.14
- Python < 3.7.11
- Python < 3.8.11
- Python < 3.9.6
- 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
- Redhat Enterprise Linux 6.0
Attack profile CVSS 3.1 · 7.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/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-2021-3737.md and follow it. Check whether this project is affected by CVE-2021-3737. 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/issue44022
- https://bugzilla.redhat.com/show_bug.cgi?id=1995162
- https://github.com/python/cpython/pull/25916
- https://github.com/python/cpython/pull/26503
- https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html
- https://ubuntu.com/security/CVE-2021-3737
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://bugs.python.org/issue44022
- https://bugzilla.redhat.com/show_bug.cgi?id=1995162
- https://github.com/python/cpython/pull/25916
References
- https://bugs.python.org/issue44022
- https://bugzilla.redhat.com/show_bug.cgi?id=1995162
- https://github.com/python/cpython/pull/25916
- https://github.com/python/cpython/pull/26503
- https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
- https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
- https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html
- https://security.netapp.com/advisory/ntap-20220407-0009/
- https://ubuntu.com/security/CVE-2021-3737
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://bugs.python.org/issue44022
- https://bugzilla.redhat.com/show_bug.cgi?id=1995162
- https://github.com/python/cpython/pull/25916
- https://github.com/python/cpython/pull/26503
- 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/2024/11/msg00024.html
- https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html
- https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html
- https://security.netapp.com/advisory/ntap-20220407-0009/
- https://ubuntu.com/security/CVE-2021-3737
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html