SUSE-SU-2026:20270-1

Vulnerability from csaf_suse - Published: 2026-01-21 13:01 - Updated: 2026-01-21 13:01
Summary
Security update for python-urllib3
Severity
Moderate
Notes
Title of the patch: Security update for python-urllib3
Description of the patch: This update for python-urllib3 fixes the following issues: - CVE-2026-21441: Fixed excessive resource consumption during decompression of data in HTTP redirect responses (bsc#1256331).
Patchnames: SUSE-SLE-Micro-6.0-566
Terms of use: CSAF 2.0 data is provided by SUSE under the Creative Commons License 4.0 with Attribution (CC-BY-4.0).
CVE-2026-21441
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Affected products
Product Identifier Version Remediation
Unresolved product id: SUSE Linux Micro 6.0:python311-urllib3-2.1.0-4.1.noarch —
Vendor Fix
Threats
Impact moderate
References
To clipboard 

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    {
      "cve": "CVE-2026-21441",
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          "text": "https://www.suse.com/security/cve/CVE-2026-21441"
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      ],
      "notes": [
        {
          "category": "general",
          "text": "urllib3 is an HTTP client library for Python. urllib3\u0027s 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 decoding or decompression based on the HTTP `Content-Encoding` header (e.g., `gzip`, `deflate`, `br`, or `zstd`). When using the streaming API, the library decompresses only the necessary bytes, enabling partial content consumption. Starting in version 1.22 and prior to version 2.6.3, for HTTP redirect responses, the library would read the entire response body to drain the connection and decompress the content unnecessarily. This decompression occurred even before any read methods were called, and configured read limits did not restrict the amount of decompressed data. As a result, there was no safeguard against decompression bombs. A malicious server could exploit this to trigger excessive resource consumption on the client. Applications and libraries are affected when they stream content from untrusted sources by setting `preload_content=False` when they do not disable redirects. Users should upgrade to at least urllib3 v2.6.3, in which the library does not decode content of redirect responses when `preload_content=False`. If upgrading is not immediately possible, disable redirects by setting `redirect=False` for requests to untrusted source.",
          "title": "CVE description"
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    }
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}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.