VYPR
High severity7.5NVD Advisory· Published Jan 10, 2017· Updated May 6, 2026

CVE-2016-6581

CVE-2016-6581

Description

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 packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
hpackPyPI
>= 1.0.0, < 2.3.02.3.0

Affected products

7
  • cpe:2.3:a:python:hpack:1.0:*:*:*:*:*:*:*+ 4 more
    • cpe:2.3:a:python:hpack:1.0:*:*:*:*:*:*:*
    • cpe:2.3:a:python:hpack:2.0:*:*:*:*:*:*:*
    • cpe:2.3:a:python:hpack:2.0.1:*:*:*:*:*:*:*
    • cpe:2.3:a:python:hpack:2.1.1:*:*:*:*:*:*:*
    • cpe:2.3:a:python:hpack:2.2:*:*:*:*:*:*:*
  • cpe:2.3:a:python:hyper:0.4:*:*:*:*:*:*:*+ 1 more
    • cpe:2.3:a:python:hyper:0.4:*:*:*:*:*:*:*
    • cpe:2.3:a:python:hyper:0.6:*:*:*:*:*:*:*

Patches

0

No patches discovered yet.

Vulnerability mechanics

AI mechanics synthesis has not run for this CVE yet.

References

7

News mentions

0

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