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Vulnerabilities

Threat intelligence · CVE-2021-39241

An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3.

Published Aug 17, 2021 · catalog updated Jun 17, 2026 · An issue was discovered

Last checked Nov 5, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2021-39241. EPSS is 1.69%. Act only if a listed version of An issue was discovered is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (An issue was discovered).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium5.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.69%
Remediation
Version ranges on file
Affected products
cpe debian/debian linux · cpe fedoraproject/fedora · cpe haproxy/haproxy

Vulnerabilities in Red Hat Products Multiple vulnerabilities have been identified in the two Red Hat products, leading to information disclosure and security bypass attacks. How it can be Exploited CVE-2021-39241: The security bypass vulnerability exists in the Red Hat OpenShift Container Platform due to insufficient validation of user-supplied input in HAProxy. The bug exists because an HTTP method name may contain

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe debian/debian linux11.0
  • cpe fedoraproject/fedora33
  • cpe haproxy/haproxy< 2.0.24
  • cpe haproxy/haproxy< 2.2.16
  • cpe haproxy/haproxy< 2.3.13
  • cpe haproxy/haproxy< 2.4.3

How to fix CVE-2021-39241

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-39241. EPSS is 1.69%. Act only if a listed version of An issue was discovered is installed.

Which versions are affected?

Compare what you have installed with debian/debian linux 11.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 1.69%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

HAProxy security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 2, 2022 · AlienVault OTX

    Detected

    Vulnerabilities in Red Hat Products Multiple vulnerabilities have been identified in the two Red Hat products, leading to information disclosure and security bypass attacks. How it can be Exploited CVE-2021-39241: The security bypass vulnerability exists in the Red Hat OpenShift Container Platform due to insufficient validation of user-supplied input in HAProxy. The bug exists because an HTTP meth

  2. Jun 17, 2026 · Monitored products — high

    Updated

    An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. An HTTP method name may contain a space followed by the name of a protected resource. It is possible that a server would interpret this as a request for that protected resource, such as in the "GET /admin? HTTP/1.1 /static/images HTTP/1.1" example.

Sources

  • CVE.orgVulnerability recordCVE-2021-39241

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2021-39241

    An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. An HTTP method name may contain a space followed by the name of a protected resource. It is possible that a server would interpret this as a request for that protected resource, such as in the "GET /admin? HTTP/1.1 /static/images HTTP/1.1" example.

    nvd.nist.gov
  • AlienVault OTXThreat intelligenceCVE-2021-39241
    otx.alienvault.com

References

Freshness

Last verified in this catalog Nov 5, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • Monitored products — highNov 2, 2026
  • AlienVault OTXNov 2, 2026