PYSEC-2026-142

    Dashboard / Vulnerabilities / PYSEC-2026-142

    PYSEC-2026-142

    Published: 13 May 2026Last Modified: 20 May 2026

    Summary:

    Details: urllib3 is an HTTP client library for Python. From 2.6.0 to before 2.7.0, urllib3 could decompress the whole response instead of the requested portion (1) during the second HTTPResponse.read(amt=N) call when the response was decompressed using the official Brotli library or (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) on the client side. This vulnerability is fixed in 2.7.0.

    References: https://github.com/urllib3/urllib3/security/advisories/GHSA-mf9v-mfxr-j63j

    Affected packages

    Package

    Name: urllib3

    Purl: pkg:pypi/urllib3

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 2.6.0
    Fixed -2.7.0

    Affected versions

    2.6.0
    2.6.1
    2.6.2
    2.6.3

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    PYSEC-2026-142 | CVE-DB