cvedb.io
CVE-2016-6581
HIGH · CVSS 7.5
EPSS exploitation probability: 0%
Published 2017-01-10T15:59:00.423 · Last modified 2026-06-17T00:51:24.253

Summary

A HTTP/2 implementation built using any version of the Python HPACK library between v1.0.0 and v2.2.0 could be targeted for a denial of service attack, specifically a so-called "HPACK Bomb" attack. This attack occurs when an attacker inserts a header field that is exactly the size of the HPACK dynamic header table into the dynamic header table. The attacker can then send a header block that is simply repeated requests to expand that field in the dynamic table. This can lead to a gigantic compression ratio of 4,096 or better, meaning that 16kB of data can decompress to 64MB of data on the target machine.

Affected products

python — hpack

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.