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CVE Record

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...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-39241 affects specific HAProxy 2.0, 2.2, 2.3, and 2.4 releases. A malformed HTTP method could confuse how HAProxy and a backend server interpret the requested resource, potentially undermining path-based protections for sensitive areas such as admin routes.

Executive priority

Treat this as a targeted remediation item for internet-facing HAProxy deployments protecting admin, API, or restricted routes. Prioritize upgrades where HAProxy is part of an access-control boundary.

Technical view

The CVE describes an HTTP parsing ambiguity in HAProxy where a method name may contain a space followed by a protected resource name. If downstream servers interpret the request differently, access controls based on the proxy's parsed path may not match backend handling.

Likely exposure

Exposure is most likely for organizations running affected HAProxy versions in front of HTTP backends, especially where HAProxy enforces or routes access to protected paths. The bundle does not identify specific configurations beyond the affected version ranges.

Exploitation context

The source bundle does not cite active exploitation, and CISA KEV status is false. The issue is security-relevant because parsing differences at a proxy boundary can create authorization bypass conditions, but exploitability depends on deployment behavior.

Researcher notes

The bundle provides affected version ranges and the parser issue description, but no CVSS, CWE, or confirmed exploitation. Analysis should focus on HAProxy-to-backend interpretation differences and whether protected resources depend on HAProxy request parsing.

Mitigation direction

  • Upgrade HAProxy 2.0 to 2.0.24 or later.
  • Upgrade HAProxy 2.2 to 2.2.16 or later.
  • Upgrade HAProxy 2.3 to 2.3.13 or later.
  • Upgrade HAProxy 2.4 to 2.4.3 or later.
  • Apply Debian or Fedora security updates where HAProxy is distro-managed.
  • Review HAProxy vendor guidance for any configuration-specific instructions.

Validation and detection

  • Inventory all HAProxy instances and record running versions.
  • Confirm each instance is outside the affected version ranges.
  • Check Debian or Fedora package advisories where applicable.
  • Review HAProxy-fronted protected routes for proxy/backend parsing dependencies.
  • Use safe vendor-approved tests to validate malformed request-line handling.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2021-39241 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
6Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

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