CVE-2020-11100Network attack vector

Process crash via HPACK table index corruption

Published Apr 2, 2020 · Updated Aug 4, 2024

Out-of-bounds write in HAProxy 1.8 through 2.1 allows remote attackers to crash the process via crafted HTTP/2 requests. In hpack_dht_insert, an empty HPACK name and value can select headroom after the table buffer wraps, corrupting the front index and miscalculating later write addresses. HTTP/2 processing must be enabled; the usual consequence is a process crash, while code execution is constrained by heap placement and address randomization.

CVSS severity8.8
High
EPSS probability60.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in HAProxy 1.8 through 2.1 allows remote attackers to crash the process via crafted HTTP/2 requests. In hpack_dht_insert, an empty HPACK name and value can select headroom after the table buffer wraps, corrupting the front index and miscalculating later write addresses. HTTP/2 processing must be enabled; the usual consequence is a process crash, while code execution is constrained by heap placement and address randomization.

The record

CVE
CVE-2020-11100
Published
Apr 2, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 2, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8OSVCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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