dbcve.org
HaproxyWeb server / proxy

CVE-2023-45539

HIGH · 8.2 CVSS v3.1 Published 2023-11-28
Fix available
A fix is available. Upgrade to 2.8.2 or later.
See remediation →
91/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
HAProxy before 2.8.2 accepts # as part of the URI component, which might allow remote attackers to obtain sensitive information or have unspecified other impact upon misinterpretation of a path_end rule, such as routing index.html#.png to a static server.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

HAProxy before 2.8.2 incorrectly includes the URI fragment identifier (#) as part of the URI when evaluating path_end rules. Since HTTP clients do not send the fragment to servers, path_end matching on 'index.html#.png' incorrectly interprets this as ending in '.png' rather than '#', allowing attackers to bypass routing rules and potentially access sensitive resources by tricking the proxy into routing requests to incorrect backends.

MitigationUpgrade HAProxy to version 2.8.2 or later, which properly handles the fragment identifier in path_end rule evaluation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
HaproxyWeb server / proxy
Affected:< 2.8.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed HAProxy version
    Run 'haproxy -v' or 'haproxy -V' to display version information
    Affected if The version displayed is earlier than 2.8.2 (for example, 2.8.1, 2.8.0, 2.7.x, 2.6.x, etc.)
  2. Identify path_end ACL rules in configuration
    Search HAProxy configuration files (typically in /etc/haproxy/haproxy.cfg or /usr/local/etc/haproxy.conf) for 'path_end' directives in acl definitions
    Affected if Any 'path_end' rules are defined in the configuration and HAProxy version is below 2.8.2
  3. Inspect frontend and backend sections using path_end
    Review the configuration around 'use_backend' or 'http-request deny' statements that reference path_end ACLs
    Affected if Requests are being routed or filtered based on path_end rules and the HAProxy version is vulnerable
  4. Test fragment identifier handling (optional validation)
    Send a test request with a URL containing a fragment, such as GET /index.html#.png, and observe which backend or rule matches
    Affected if The request is routed as if the path ends in '.png' rather than being rejected or routed based on the actual path before the '#' character

A user is affected if running HAProxy version earlier than 2.8.2 and using path_end ACL rules in their configuration to make routing or access control decisions.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.8.2 or later
Fixed in 2.8.2
Interim mitigation

Upgrade HAProxy to version 2.8.2 or later, which properly handles the fragment identifier in path_end rule evaluation.

Recommended fix High confidence

HAProxy 2.8.2 or later

  1. Backup your current HAProxy configuration files (typically in /etc/haproxy/)
  2. Check your current HAProxy version using 'haproxy -v' or 'haproxy -V'
  3. Upgrade HAProxy to version 2.8.2 or later using your system's package manager (e.g., apt-get update && apt-get install haproxy=2.8.2*, yum update haproxy, or compile from source)
  4. Verify the new version is installed: 'haproxy -v'
  5. Test your configuration for syntax errors: 'haproxy -c -f /etc/haproxy/haproxy.cfg'
  6. Restart HAProxy to load the new version: 'systemctl restart haproxy' or 'service haproxy restart'
  7. Verify HAProxy is running correctly: 'systemctl status haproxy'
Caveat Review HAProxy 2.8.0-2.8.2 release notes for any behavioral changes; some ACL rules or path matching may behave differently with proper fragment handling

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Haproxy Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-45539 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data