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CVE-2016-6581 HPACK Denial of Service vulnerability (HPACK Bomb)

HighCVSS 7.5 EPSS 1.9%
Published
Updated
Exploit status
No public exploit known
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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 products

ProductAffected versionsFixed in
pypi hpack(PyPI) >= 1.0.0, < 2.3.0 2.3.0
pypi hpack(PyPI) = 1.0.0 No fix listed
pypi hpack(PyPI) = 1.0.1 No fix listed
pypi hpack(PyPI) = 1.1.0 No fix listed
pypi hpack(PyPI) = 2.0.0 No fix listed
pypi hpack(PyPI) = 2.0.1 No fix listed
pypi hpack(PyPI) = 2.1.0 No fix listed
pypi hpack(PyPI) = 2.1.1 No fix listed
pypi hpack(PyPI) = 2.2.0 No fix listed
pypi hpack(PyPI) < 2.3.0 2.3.0
debian/python-hpack(Debian:12) < 2.3.0-1 2.3.0-1
debian/python-hpack(Debian:13) < 2.3.0-1 2.3.0-1
debian/python-hpack(Debian:14) < 2.3.0-1 2.3.0-1
python hpack = 1.0 No fix listed
python hpack = 2.0 No fix listed
python hpack = 2.0.1 No fix listed
python hpack = 2.1.1 No fix listed
python hpack = 2.2 No fix listed
python hyper = 0.4 No fix listed
python hyper = 0.6 No fix listed

References