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CVE-2026-44432 high CVSS 7.5

Vulnerability in urllib3 (CVE-2026-44432)

Summary

Vulnerability in urllib3 (CVE-2026-44432). Risk of unauthorized operations or information disclosure. Exploitable via gzip. Mitigation: upgrade to 2.7.0 or later.

Original description

The description as published by the source.

Impact

urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once.

urllib3 can perform decompression based on the HTTP Content-Encoding header (e.g., gzip, deflate, br, or zstd). When using the streaming API since version 2.6.0, the library decompresses only the necessary bytes, enabling partial content consumption.

However, urllib3 before version 2.7.0 could still decompress the whole response instead of the requested portion in two cases:

  1. During the second HTTPResponse.read(amt=N) call when the response was decompressed using the official Brotli library.
  2. When HTTPResponse.drain_conn() was called after the response had been read and decompressed partially (compression algorithm did not matter here).

These issues could cause urllib3 to fully decode a small amount of highly compressed data in a single operation. This could result in excessive resource consumption (high CPU usage and massive memory allocation for the decompressed data; CWE-409) on the client side.

Affected usages

Applications and libraries using urllib3 versions earlier than 2.7.0 may be affected when streaming compressed responses from untrusted sources in either of these cases, unless decompression is explicitly disabled:

  1. A response…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-44432 has been found in urllib3.
Attackers can target a specific entry point like gzip over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade urllib3 to 2.7.0 or later.
If unsure, ask your IT team or search "urllib3 CVE-2026-44432" on the vendor's site.

CVE-2026-44432 (urllib3) — CWE-409 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: gzip / deflate / zstd
Patched: 2.7.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-409) exists in urllib3. Attackers reach the vulnerable code path via gzip without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of urllib3. Attack surface: gzip / deflate / zstd.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.7.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'urllib3' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'urllib3' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で urllib3 を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade urllib3 to 2.7.0

    ステージング環境で 2.7.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

pip urllib3
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.7.0"}]}]
PyPI urllib3
[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.0"},{"fixed":"2.7.0"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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