Home/CVE/A HTTP/2 implementation built using any version of the Python HPACK library between v1.0.0 and v2.2.0 could be targeted
CVE

CVE-2016-6581

A HTTP/2 implementation built using any version of the Python HPACK library between v1.0.0 and v2.2.0 could be targeted

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.

HIGH · CVSS 7.5 EPSS 0.00373
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules1 YARA rules0
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Affected Products & Versions

2
python hpackall versions
python hyperall versions
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Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
PyPI hpack HIGH fixed in 2.3.0
◈

Sigma Hunt Rules

1
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productmediumSuspicious Hyper-V Cmdlets
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Scoring & Timeline

7.5
HIGH · CVSS v3.0 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD10 Jan 2017 · 03:59 PM
CVSS VectorCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
⚑

Vendor Advisories

2
suse-csafopenSUSE-SU-2024:14140-1
suse-csafopenSUSE-SU-2024:11230-1
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
http://www.securityfocus.com/bid/92315Third Party AdvisoryVDB Entry
https://python-hyper.org/hpack/en/latest/security/CVE-2016-6581.htmlMitigationVendor Advisory
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