Allocation of Resources Without Limits or Throttling Affecting python3-hpack package, versions <0:4.0.0-2.amzn2023.0.3


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.3% (21st percentile)

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  • Snyk IDSNYK-AMZN2023-PYTHON3HPACK-20849293
  • published13 Oct 2026
  • disclosed23 Sept 2026

Introduced: 23 Sep 2026

NewCVE-2026-59980  (opens in a new tab)
CWE-770  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 python3-hpack to version 0:4.0.0-2.amzn2023.0.3 or higher.
This issue was patched in ALAS2023-2026-3159.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3-hpack package and not the python3-hpack package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of 0xFF values to prevent malicious use.

CVSS Base Scores

version 3.1