CVE-2019-20800Public exploitNetwork attack vector

Unauthenticated server crash via excess CGI headers

Published May 17, 2020 · Updated Aug 5, 2024

Out-of-bounds write in Cherokee 1.2.104 and earlier allows remote attackers to crash CGI-enabled servers via excessive HTTP headers. The cherokee_handler_cgi_add_env_pair function appends header-derived entries to the fixed-size envp array and increments envp_last without enforcing ENV_VAR_NUM. An unauthenticated request must reach a CGI-handled path; enough repeated headers drive the index beyond the array and terminate the server process.

CVSS severity9.8
Critical
EPSS probability2.15%
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 Cherokee 1.2.104 and earlier allows remote attackers to crash CGI-enabled servers via excessive HTTP headers. The cherokee_handler_cgi_add_env_pair function appends header-derived entries to the fixed-size envp array and increments envp_last without enforcing ENV_VAR_NUM. An unauthenticated request must reach a CGI-handled path; enough repeated headers drive the index beyond the array and terminate the server process.

The record

CVE
CVE-2019-20800
Published
May 17, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 17, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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

7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

Public exploit references

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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