SB20260509126 - Multiple vulnerabilities in urllib3

Description

This security bulletin contains information about 2 vulnerabilities.

1) Improper handling of highly compressed data (CVE-ID: CVE-2026-44432)

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper handling of highly compressed data in the urllib3 streaming API when processing compressed HTTP responses from untrusted sources. A remote attacker can send a highly compressed response to cause a denial of service.

Exploitation requires either incremental reads of a Brotli-encoded response with at least two read or stream calls while using the official Brotli library, or calling HTTPResponse.drain_conn() after decompression has already started.

2) Information disclosure (CVE-ID: CVE-2026-44431)

The vulnerability allows a remote attacker to disclose sensitive information.

The vulnerability exists due to exposure of sensitive information in ProxyManager.connection_from_url().urlopen() when following cross-origin redirects with assert_same_host=False through a proxy. A remote attacker can trigger a cross-origin redirect to disclose sensitive information.

Sensitive headers such as Authorization, Cookie, and Proxy-Authorization may be forwarded across origins in this low-level redirect flow.

Remediation

Install update from vendor's website.

References

• https://github.com/urllib3/urllib3/security/advisories/GHSA-mf9v-mfxr-j63j
• https://github.com/urllib3/urllib3/security/advisories/GHSA-qccp-gfcp-xxvc