Medium severity · published May 13, 2026
CVE-2026-44431
urllib3: Sensitive headers forwarded across origins in proxied low-level redirects
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
urllib3 is an HTTP client library for Python. From 1.23 to before 2.7.0, cross-origin redirects followed from the low-level API via ProxyManager.connection_from_url().urlopen(..., assert_same_host=False) still forward these sensitive headers. This vulnerability is fixed in 2.7.0.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 26% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UR
urllib3 · urllib3
>= 1.23, < 2.7.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44431
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-44431
Mitigation
https://github.com/urllib3/urllib3/security/advisories/GHSA-qccp-gfcp-xxvc
lists.debian.org
https://lists.debian.org/debian-lts-announce/2026/06/msg00040.html
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