Kurz gesagt
- CVE-2026-59980 ist eine Schwachstelle (MITTEL (CVSS 6.3)) in hpack.
- Wahrscheinlichkeit einer Ausnutzung in den nächsten 30 Tagen (EPSS): 0.30%, höher als bei 22.9% aller Schwachstellen.
- Abhilfe: auf 4.2.0 oder neuer aktualisieren.
| Package | Affected versions | Patched versions |
|---|
| hpack PyPI | < 4.2.0
| 4.2.0
|
Description
Impact
Users of the python-hyper/hpack library, most commonly used as downstream dependency of the python-hyper/h2 library (an HTTP/2 client and server implementation). 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.
Patches
A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation.
Workarounds
Sanitize input to hpack decoder for long sequences of 0xFF values to prevent malicious use.
NVD description
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.
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