Resource Management Errors Affecting python-hpack package, versions <2.3.0-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-ECHOLATEST-PYTHONHPACK-20138279
- published25 Sept 2026
- disclosed10 Jan 2017
Introduced: 10 Jan 2017
CVE-2016-6581 (opens in a new tab)How to fix?
Upgrade Echo:latest python-hpack to version 2.3.0-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream python-hpack package and not the python-hpack package as distributed by Echo.
See How to fix? for Echo:latest relevant fixed versions and status.
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.