CVE-2026-44431 urllib3: Sensitive headers forwarded across origins in proxied low-level redirects
High 8.2
Published
Updated
Check this codebase for CVE-2026-44431 and fix it if it is affected.
What it is: CVE-2026-44431 is a high-severity vulnerability in urllib3, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-44431 in the wild and no public exploit code.
Affected packages and fixed versions:
- urllib3 (PyPI): affected from 1.23; fixed in 2.7.0
- urllib3 (PyPI): affected from 1.23; fixed in 2.7.0
- urllib3 (PyPI): affected from 1.23; fixed in 2.7.0
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2026-44431/ (Markdown: https://insights.sbomify.com/CVE-2026-44431/index.md)
Attackers can steal sensitive headers during cross-origin redirects in urllib3's low-level API when using ProxyManager with assert_same_host disabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44431?
CVE-2026-44431 is a high-severity vulnerability in urllib3, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-200
Which versions are affected by CVE-2026-44431?
3 open source packages ship an affected version, including urllib3. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
urllib3 PyPI | From 1.23 | 2.7.0 |
urllib3 PyPI | From 1.23 | 2.7.0 |
urllib3 PyPI | From 1.23 | 2.7.0 |
Linux distribution packages (37)
fence-agents-aliyun AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-all AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-amt-ws AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-apc AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-apc-snmp AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-aws AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-azure-arm AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-bladecenter AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-brocade AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-cisco-mds AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-cisco-ucs AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-common AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-compute AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-drac5 AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-eaton-snmp AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-emerson AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-eps AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-gce AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-heuristics-ping AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-hpblade AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ibm-powervs AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ibm-vpc AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ibmblade AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ifmib AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ilo-moonshot AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ilo-mp AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ilo-ssh AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ilo2 AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-intelmodular AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ipdu AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-ipmilan AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-kdump AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-kubevirt AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-lpar AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-mpath AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-nutanix-ahv AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
fence-agents-openstack AlmaLinux:8 | All versions | 4.2.1-129.el8_10.28 |
Products include Python Urllib3.
How do I fix CVE-2026-44431?
Upgrade urllib3 to 2.7.0 or later.
Is CVE-2026-44431 being exploited?
There is no known exploitation of CVE-2026-44431 in the wild and no public exploit code.
Other vulnerabilities in urllib3
- CVE-2026-97689 urllib3: HTTPResponse.stream()/read_chunked() buffers an unbounded chunk-size line into memory
- CVE-2026-44432 urllib3: Decompression-bomb safeguards bypassed in parts of the streaming API
- CVE-2026-21441 urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API)
- CVE-2025-66418 urllib3 allows an unbounded number of links in the decompression chain
- CVE-2025-66471 urllib3 Streaming API improperly handles highly compressed data
Sources
Also known as ALSA-2026:36732, ALSA-2026:47126, ALSA-2026:49927, AZL-86862, BELL-CVE-2026-44431, CLEANSTART-2026-KM03146 and 72 more.