CVE catalog
CVE-2021-3737
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
- Severity
- High · CVSS 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C - Published
- Updated
- Source
- [NVD] · [CVE record]
- EPSS
- 13.17% · Oct 25, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | pypy3 | sid | 8.0.1+dfsg-1 | fixed |
| Debian | pypy3 | forky | 8.0.1+dfsg-1 | fixed |
| Debian | pypy3 | trixie | 7.3.19+dfsg-2 | fixed |
| Debian | pypy3 | bookworm | 7.3.11+dfsg-2+deb12u3 | fixed |
| Cpe | python | Not reported | 3.6.14 | fixed |
| Cpe | python | Not reported | 3.7.11 | fixed |
| Cpe | python | Not reported | 3.8.11 | fixed |
| Cpe | python | Not reported | 3.9.6 | fixed |
| Cpe | codeready_linux_builder | Not reported | Not reported | unknown |
| Cpe | codeready_linux_builder_for_ibm_z_systems | Not reported | Not reported | unknown |
| Cpe | codeready_linux_builder_for_power_little_endian | Not reported | Not reported | unknown |
| Cpe | enterprise_linux | Not reported | Not reported | unknown |
| Cpe | enterprise_linux | Not reported | Not reported | unknown |
| Cpe | enterprise_linux | Not reported | Not reported | unknown |
| Cpe | enterprise_linux_for_ibm_z_systems | Not reported | Not reported | unknown |
| Cpe | enterprise_linux_for_power_little_endian | Not reported | Not reported | unknown |
| Cpe | fedora | Not reported | Not reported | unknown |
| Cpe | fedora | Not reported | Not reported | unknown |
| Cpe | ubuntu_linux | Not reported | Not reported | unknown |
| Cpe | ubuntu_linux | Not reported | Not reported | unknown |
| Cpe | ubuntu_linux | Not reported | Not reported | unknown |
| Cpe | ubuntu_linux | Not reported | Not reported | unknown |
| Cpe | ubuntu_linux | Not reported | Not reported | unknown |
| Cpe | hci | Not reported | Not reported | unknown |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a2-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a3-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a3-2 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a3-3 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a4-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b1-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b1-1build1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b2-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b3-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0-1~18.04 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.1-1~18.04 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.3-2~18.04.1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.5-2~18.04 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.5-2~18.04.4 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.5-2ubuntu1~18.04.2 | fixed |
| Ubuntu | python3.8 | 18.04 | 3.8.0-3~18.04 | vulnerable |
| Ubuntu | python3.8 | 18.04 | 3.8.0-3~18.04.1 | vulnerable |
| Ubuntu | python3.8 | 18.04 | 3.8.0-3ubuntu1~18.04.2 | fixed |
| Ubuntu | python3.4 | pro | 3.4~b1-0ubuntu3 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~b1-4ubuntu4 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~b1-4ubuntu6 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~b1-5ubuntu2 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~b2-1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~b3-1ubuntu1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~rc1-1build1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~rc2-1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4~rc3-0ubuntu1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.0-1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.0-2ubuntu1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.0-2ubuntu1.1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.1 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.3 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.4 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.5 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.6 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7+esm2 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7+esm4 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7+esm6 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7+esm7 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7+esm8 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7+esm10 | vulnerable |
| Ubuntu | python3.4 | pro | 3.4.3-1ubuntu1~14.04.7+esm11 | fixed |
| Ubuntu | python3.5 | pro | 3.5.0-3 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.0-3ubuntu1 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1~rc1-2ubuntu1 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-1 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-2 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-3 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-5 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-6ubuntu1 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-6ubuntu2 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-9ubuntu1 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.1-10 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2~16.01 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2~16.04 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.1 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.2 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.3 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.4 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.5 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.8 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.9 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.10 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.11 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.12 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.13 | vulnerable |
| Ubuntu | python3.5 | pro | 3.5.2-2ubuntu0~16.04.13+esm1 | fixed |
| Ubuntu | python3.6 | 18.04 | 3.6.3-1ubuntu1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.4~rc1-1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.4~rc1-2 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.4-1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.4-2 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.4-3build1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.4-4 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.5~rc1-1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.5-3 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.6-1~18.04 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.7-1~18.04 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.8-1~18.04.1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.8-1~18.04.2 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.8-1~18.04.3 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.9-1~18.04 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.9-1~18.04ubuntu1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.9-1~18.04ubuntu1.1 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.9-1~18.04ubuntu1.3 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.9-1~18.04ubuntu1.4 | vulnerable |
| Ubuntu | python3.6 | 18.04 | 3.6.9-1~18.04ubuntu1.6 | fixed |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a2-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a3-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a3-2 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a3-3 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~a4-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b1-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b1-1build1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b2-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0~b3-1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.0-1~18.04 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.1-1~18.04 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.3-2~18.04.1 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.5-2~18.04 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.5-2~18.04.4 | vulnerable |
| Ubuntu | python3.7 | 18.04 | 3.7.5-2ubuntu1~18.04.2 | fixed |
| Ubuntu | python3.8 | 18.04 | 3.8.0-3~18.04 | vulnerable |
| Ubuntu | python3.8 | 18.04 | 3.8.0-3~18.04.1 | vulnerable |
| Ubuntu | python3.8 | 18.04 | 3.8.0-3ubuntu1~18.04.2 | fixed |
| Ubuntu | python3.8 | 20.04 | 3.8.0-1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-2 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-3 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-4 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-5 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.1-2ubuntu3 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2~rc1-1ubuntu1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1ubuntu1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1ubuntu1.1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1ubuntu1.2 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.5-1~20.04 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.5-1~20.04.2 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.5-1~20.04.3 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.10-0ubuntu1~20.04 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.10-0ubuntu1~20.04.1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.10-0ubuntu1~20.04.2 | fixed |
| Ubuntu | python3.9 | 20.04 | 3.9.0~rc1-1~20.04 | vulnerable |
| Ubuntu | python3.9 | 20.04 | 3.9.0-5~20.04 | vulnerable |
| Ubuntu | python3.9 | 20.04 | 3.9.5-3~20.04.1 | vulnerable |
| Ubuntu | python3.9 | 20.04 | 3.9.5-3ubuntu0~20.04.1 | fixed |
| Ubuntu | python3.8 | 20.04 | 3.8.0-1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-2 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-3 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-4 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.0-5 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.1-2ubuntu3 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2~rc1-1ubuntu1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1ubuntu1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1ubuntu1.1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.2-1ubuntu1.2 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.5-1~20.04 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.5-1~20.04.2 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.5-1~20.04.3 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.10-0ubuntu1~20.04 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.10-0ubuntu1~20.04.1 | vulnerable |
| Ubuntu | python3.8 | 20.04 | 3.8.10-0ubuntu1~20.04.2 | fixed |
| Ubuntu | python3.9 | 20.04 | 3.9.0~rc1-1~20.04 | vulnerable |
| Ubuntu | python3.9 | 20.04 | 3.9.0-5~20.04 | vulnerable |
| Ubuntu | python3.9 | 20.04 | 3.9.5-3~20.04.1 | vulnerable |
| Ubuntu | python3.9 | 20.04 | 3.9.5-3ubuntu0~20.04.1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | pypy3 | source | sid | 7.3.8+dfsg-1 | not yet assigned | Not reported | Not reported |
| Debian | pypy3 | source | forky | 7.3.8+dfsg-1 | not yet assigned | Not reported | Not reported |
| Debian | pypy3 | source | trixie | 7.3.8+dfsg-1 | not yet assigned | Not reported | Not reported |
| Debian | pypy3 | source | bookworm | 7.3.8+dfsg-1 | not yet assigned | Not reported | Not reported |
| Cpe | python | cpe | Not reported | 3.6.14 | Not reported | NVD-CVE-2021-3737 | Not reported |
| Cpe | python | cpe | Not reported | 3.7.11 | Not reported | NVD-CVE-2021-3737 | Not reported |
| Cpe | python | cpe | Not reported | 3.8.11 | Not reported | NVD-CVE-2021-3737 | Not reported |
| Cpe | python | cpe | Not reported | 3.9.6 | Not reported | NVD-CVE-2021-3737 | Not reported |
| Ubuntu | python3.7 | deb | 18.04 | 3.7.5-2ubuntu1~18.04.2 | Not reported | USN-5200-1 | Not reported |
| Ubuntu | python3.8 | deb | 18.04 | 3.8.0-3ubuntu1~18.04.2 | Not reported | USN-5200-1 | Not reported |
| Ubuntu | python3.4 | deb | pro | 3.4.3-1ubuntu1~14.04.7+esm11 | Not reported | UBUNTU-CVE-2021-3737 | Not reported |
| Ubuntu | python3.5 | deb | pro | 3.5.2-2ubuntu0~16.04.13+esm1 | Not reported | UBUNTU-CVE-2021-3737 | Not reported |
| Ubuntu | python3.6 | deb | 18.04 | 3.6.9-1~18.04ubuntu1.6 | Not reported | UBUNTU-CVE-2021-3737 | Not reported |
| Ubuntu | python3.7 | deb | 18.04 | 3.7.5-2ubuntu1~18.04.2 | Not reported | UBUNTU-CVE-2021-3737 | Not reported |
| Ubuntu | python3.8 | deb | 18.04 | 3.8.0-3ubuntu1~18.04.2 | Not reported | UBUNTU-CVE-2021-3737 | Not reported |
| Ubuntu | python3.8 | deb | 20.04 | 3.8.10-0ubuntu1~20.04.2 | Not reported | UBUNTU-CVE-2021-3737 | Not reported |
| Ubuntu | python3.9 | deb | 20.04 | 3.9.5-3ubuntu0~20.04.1 | Not reported | UBUNTU-CVE-2021-3737 | Not reported |
| Ubuntu | python3.8 | deb | 20.04 | 3.8.10-0ubuntu1~20.04.2 | Not reported | USN-5201-1 | Not reported |
| Ubuntu | python3.9 | deb | 20.04 | 3.9.5-3ubuntu0~20.04.1 | Not reported | USN-5201-1 | Not reported |
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [pypy3]Fixed
Details (2)
7.3.11+dfsg-2+deb12u3· amd64 · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
7.3.11+dfsg-2+deb12u3· arm64 · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
- [pypy3-dev]Fixed
Source package: [pypy3]
Details (2)
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
- [pypy3-doc]Fixed
Source package: [pypy3]
Details (2)
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
- [pypy3-lib]Fixed
Source package: [pypy3]
Details (2)
7.3.11+dfsg-2+deb12u3· amd64 · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
7.3.11+dfsg-2+deb12u3· arm64 · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
- [pypy3-lib-testsuite]Fixed
Source package: [pypy3]
Details (2)
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
- [pypy3-tk]Fixed
Source package: [pypy3]
Details (2)
7.3.11+dfsg-2+deb12u3· amd64 · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
7.3.11+dfsg-2+deb12u3· arm64 · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
- [pypy3-venv]Fixed
Source package: [pypy3]
Details (2)
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
7.3.11+dfsg-2+deb12u3· all · bookwormFixed · Fixed:
7.3.8+dfsg-1nvd · pypy3 · debian · bookworm
Observed:
References
- [https://cert-portal.siemens.com/productcert/csaf/ssa-398330.json]
- [https://ftp.suse.com/pub/projects/security/csaf/rhsa-2022_1821.json]
- [https://nvd.nist.gov/vuln/detail/CVE-2021-3737]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2021-3737]
- [https://osv.dev/vulnerability/USN-5200-1]
- [https://osv.dev/vulnerability/USN-5201-1]
- [https://security-tracker.debian.org/tracker/CVE-2021-3737]
- [https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-3737.json]
- [https://wid.cert-bund.de/.well-known/csaf/white/2022/wid-sec-w-2022-0011.json]
[CERT-Bund public advisories] · [CISA cybersecurity advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]