CVE catalog
CVE-2021-28363
python-urllib3: CVE-2021-28363
- Severity
- Medium · CVSS 6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 2.17% · Oct 25, 2026
The urllib3 library 1.26.x before 1.26.4 for Python omits SSL certificate validation in some cases involving HTTPS to HTTPS proxies. The initial connection to the HTTPS proxy (if an SSLContext isn't given via proxy_config) doesn't verify the hostname of the certificate. This means certificates for different servers that still validate properly with the default urllib3 SSLContext will be silently accepted.
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 | python-urllib3 | sid | 2.8.0-2 | fixed |
| Debian | python-urllib3 | forky | 2.8.0-2 | fixed |
| Debian | python-urllib3 | trixie | 2.3.0-3+deb13u2 | fixed |
| Debian | python-urllib3 | trixie-security | 2.3.0-3+deb13u2 | fixed |
| Debian | python-urllib3 | bookworm | 1.26.12-1+deb12u4 | fixed |
| Debian | python-urllib3 | bookworm-security | 1.26.12-1+deb12u4 | fixed |
| Cpe | urllib3 | Not reported | 1.26.4 | fixed |
| Cpe | fedora | Not reported | Not reported | unknown |
| Cpe | peoplesoft_enterprise_peopletools | Not reported | Not reported | unknown |
| Alpine | py3-urllib3 | 3.14 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.15 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.16 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.17 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.18 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.19 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.20 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.21 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.22 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.23 | 1.26.4-r0 | fixed |
| Alpine | py3-urllib3 | 3.24 | 1.26.4-r0 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | python-urllib3 | source | sid | 1.26.4-1 | not yet assigned | Not reported | Not reported |
| Debian | python-urllib3 | source | forky | 1.26.4-1 | not yet assigned | Not reported | Not reported |
| Debian | python-urllib3 | source | trixie | 1.26.4-1 | not yet assigned | Not reported | Not reported |
| Debian | python-urllib3 | source | bookworm | 1.26.4-1 | not yet assigned | Not reported | Not reported |
| Cpe | urllib3 | cpe | Not reported | 1.26.4 | Not reported | NVD-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.14 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.15 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.16 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.17 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.18 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.19 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.20 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.21 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.22 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.23 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
| Alpine | py3-urllib3 | apk | 3.24 | 1.26.4-r0 | Not reported | ALPINE-CVE-2021-28363 | Not reported |
OpenFactory catalog packages
Matching against OpenFactory catalog package versions is in progress.
[Debian 12 (Bookworm)]
- [python3-urllib3]Unknown
Source package: [python-urllib3]
Details (4)
1.26.12-1+deb12u4· all · bookwormFixed · Fixed:
1.26.4-1dsa · python-urllib3 · debian · bookworm
1.26.12-1+deb12u4· all · bookwormFixed · Fixed:
1.26.4-1dsa · python-urllib3 · debian · bookworm
1.26.12-1+deb12u4· all · bookworm-securityFixed · Fixed:
1.26.4-1dsa · python-urllib3 · debian · bookworm
1.26.12-1+deb12u4· all · bookworm-securityFixed · Fixed:
1.26.4-1dsa · python-urllib3 · debian · bookworm
Observed:
References
- [https://cert-portal.siemens.com/productcert/csaf/ssa-398330.json]
- [https://ftp.suse.com/pub/projects/security/]
- [https://nvd.nist.gov/vuln/detail/CVE-2021-28363]
- [https://osv.dev/vulnerability/ALPINE-CVE-2021-28363]
- [https://security-tracker.debian.org/tracker/CVE-2021-28363]
- [https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-28363.json]
[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]