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Big Ip Access Policy ManagerApplication · F5

CVE-2026-39455

HIGH · 7.5 CVSS v3.1 Published 2026-05-13
Fix available
A fix is available. Upgrade to after 17.5.1 or later.
See remediation →
84/100
Remediation priority · High
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
When the BIG-IP Configuration utility is configured to use Lightweight Directory Access Protocol (LDAP) authentication, undisclosed traffic can cause the httpd process to exhaust the available file descriptors.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

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 · moderate confidence

When the BIG-IP Configuration utility is configured to use LDAP authentication, undisclosed traffic can cause the httpd process to exhaust available file descriptors, resulting in denial of service. This is a resource exhaustion vulnerability specific to the LDAP authentication configuration path.

MitigationContact F5 Networks for the applicable software update. Until a patch is available, consider restricting LDAP authentication sources or implementing network-level controls to limit suspicious traffic.

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
Big Ip Access Policy ManagerApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0
Big Ip Advanced Firewall ManagerApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0
Big Ip Advanced Web Application FirewallApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0
Big Ip AnalyticsApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0
Big Ip Application Acceleration ManagerApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0
Big Ip Application Security ManagerApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0
Big Ip Application Visibility And ReportingApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0
Big Ip Automation ToolchainApplication
Affected:>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1>= 16.1.0, <= 16.1.6= 21.0.0

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
None
Integrity
None
Availability
High

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

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. Confirm LDAP authentication is configured for the Configuration utility
    Run 'tmsh list auth ldap' or inspect /config/bigip.conf for ldap authentication server settings
    Affected if LDAP authentication is enabled for the Configuration utility (the vulnerability only triggers when LDAP auth is in use)
  2. Identify the installed BIG-IP version
    Run 'tmsh show sys version' or check the file /etc/product_version
    Affected if The version is 17.1.0 through 17.1.3, 17.5.0 through 17.5.1, 16.1.0 through 16.1.6, or exactly 21.0.0
  3. Check current httpd process file descriptor usage
    Run 'ps aux | grep httpd' to obtain the PID, then check lsof or /proc/PID/fd for open file descriptors. Compare against system ulimit -n
    Affected if The httpd process has opened file descriptors approaching or hitting the system limit, indicating exhaustion
  4. Monitor for LDAP auth-related connection accumulation
    Run 'netstat -an | grep :443' or similar to observe connection states from LDAP auth sources, check for unusual connection growth
    Affected if A large number of connections are building up, particularly from LDAP authentication traffic sources

You are affected if LDAP authentication is configured for the Configuration utility AND your BIG-IP version falls within the affected ranges (17.1.0-17.1.3, 17.5.0-17.5.1, 16.1.0-16.1.6, or 21.0.0), with symptoms including rising httpd file descriptor usage.

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.

From vendor data
Upgrade available Upgrade to a release after 17.5.1
Interim mitigation

Contact F5 Networks for the applicable software update. Until a patch is available, consider restricting LDAP authentication sources or implementing network-level controls to limit suspicious traffic.

Fix this in Big Ip Access Policy Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,330
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,728.

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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-2026-39455 in production — separate from our analysis above.

No notes yet

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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