StackPrism

PyPI package

urllib3 2.1.0 vulnerabilities, and the version that fixes all of them

urllib3 2.1.0 has 8 known vulnerabilities (6 rated high or critical); 2.8.0 fixes all of them.

PyPI (opens in a new tab) describes it as “HTTP library with thread-safe connection pooling, file post, and more.”

Known vulnerabilities
8
6 rated high or critical
Released
Nov 13, 2023
Latest is 2.8.0
Licence
MIT
OpenSSF Scorecard
8.6/10
urllib3/urllib3 (opens in a new tab)
Dependencies
None
Resolved by deps.dev

What to upgrade to

2.8.0 is the closest release with no known vulnerabilities.

  • 2.8.0Upgrade to this

    Fixes all 8 known vulnerabilities and the newest 2.x release and the latest release. Released Sep 15, 2026.

    No known vulnerabilities

2.8.0 came out on Sep 15, 2026. A coding agent trained before then doesn’t know it exists, so it may suggest an older release. AI knowledge cutoff dates

Hand the fix to your coding agent

One task with the upgrade, the file to change and why. Paste it into Claude Code, Cursor or Codex.

Findings

Every advisory for urllib3 2.1.0

Known exploited first (CISA KEV), then by how likely they are to be exploited (FIRST EPSS), then by severity. Each id links to its OSV.dev record.

  1. CriticalCVE-2026-21441 on OSV.dev (opens in a new tab)GHSA-38jv-5279-wg99EPSS: top 14%

    Decompression-bomb safeguards bypassed when following HTTP redirects (streaming API)

    Fixed in 2.6.3. Published Jan 7, 2026.

  2. WarningCVE-2024-37891 on OSV.dev (opens in a new tab)GHSA-34jh-p97f-mpxfEPSS: top 34%

    urllib3's Proxy-Authorization request header isn't stripped during cross-origin redirects

    Fixed in 2.2.2. Published Jun 17, 2024.

  3. CriticalCVE-2025-66471 on OSV.dev (opens in a new tab)GHSA-2xpw-w6gg-jr37EPSS: top 49%

    urllib3 streaming API improperly handles highly compressed data

    Fixed in 2.6.0. Published Dec 5, 2025.

  4. CriticalCVE-2025-66418 on OSV.dev (opens in a new tab)GHSA-gm62-xv2j-4w53EPSS: top 49%

    urllib3 allows an unbounded number of links in the decompression chain

    Fixed in 2.6.0. Published Dec 5, 2025.

  5. WarningCVE-2025-50181 on OSV.dev (opens in a new tab)GHSA-pq67-6m6q-mj2vEPSS: top 61%

    urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation

    Fixed in 2.5.0. Published Jun 18, 2025.

  6. CriticalCVE-2026-44431 on OSV.dev (opens in a new tab)GHSA-qccp-gfcp-xxvcEPSS: top 75%

    urllib3: Sensitive headers forwarded across origins in proxied low-level redirects

    Fixed in 2.7.0. Published May 11, 2026.

  7. CriticalCVE-2026-97689 on OSV.dev (opens in a new tab)GHSA-vxq7-64xx-v4gwEPSS: top 75%

    urllib3: HTTPResponse.stream()/read_chunked() buffers an unbounded chunk-size line into memory

    Fixed in 2.8.0. Published Sep 30, 2026.

  8. CriticalCVE-2026-97687 on OSV.dev (opens in a new tab)GHSA-8988-9cw3-xx77EPSS: top 91%

    urllib3: HTTPS proxy TLS configuration may be ignored or overridden

    Fixed in 2.8.0. Published Sep 30, 2026.

Is urllib3 the only one?

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How this page is checked

StackPrism asks OSV.dev which advisories affect exactly urllib3 2.1.0, merges duplicates filed under several ids, and ranks them with CISA’s Known Exploited Vulnerabilities list and FIRST EPSS. Release dates and deprecation come from deps.dev and PyPI. No AI writes this page: every sentence comes from that data, refreshed every few hours.

Last checked against PyPI, OSV.dev, deps.dev, CISA KEV and FIRST EPSS.