hpack: Unbounded variable integer decoding can cause run-away computation on malformed input

TRUNG BÌNH 6.3CVE-2026-59980 · GHSA-8v8h-hg4w-mvq2 · PYSEC-2026-4053 · Công bố 23/09/2026 · cập nhật 30/09/2026

Tóm tắt nhanh

CVE-2026-59980 là lỗ hổng mức TRUNG BÌNH (CVSS 6.3) ảnh hưởng hpack.
Xác suất bị khai thác trong 30 ngày tới (EPSS): 0.30%, cao hơn 22.9% các lỗ hổng khác.
Cách xử lý: cập nhật lên 4.2.0 hoặc mới hơn.

Gói / sản phẩm	Phiên bản bị ảnh hưởng	Phiên bản đã vá
hpack PyPI	`< 4.2.0`	`4.2.0`

Mô tả

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.

Mô tả của NVD

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.