CVE-2026-94127 — F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability
When a BIG-IP APM access policy and an OAuth profile are configured on a virtual server, specific malicious traffic can lead to remote code execution (RCE). This vulnerability is only present when BIG-IP APM is configured as an OAuth Authorization Server. Deployments using APM strictly as an OAuth Client / Resource Server (without OAuth authorization server profiles configured) are not affected by this vulnerability. Impact: This vulnerability allows an unauthenticated attacker to perform remote code execution. The BIG-IP system in Appliance mode is also vulnerable. This is a data plane issue; there is no control plane exposure. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Confirmed exploitation (CISA KEV)+35
- Public exploit/PoC (github)+6
- EPSS 2.2% (30-day exploitation probability)+12
- Technical severity (critical)+10
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
CISA required action CISA
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
US federal deadline: Sep 25, 2026 — passed 20 day(s) ago
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (F5 BIG-IP, F5 Big-ip Access Policy Manager).
- Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| F5 | BIG-IP | ≥ 21.1.0 and < Hotfix-BIGIP-21.1.0.2.0.30.22-ENG≥ 17.5.0 and < Hotfix-BIGIP-17.5.1.9.0.160.12-ENG≥ 17.1.0 and < Hotfix-BIGIP-17.1.3.5.0.41.14-ENG | Vulnerable | CVE Program (cve.org) e CISA ADP |
| F5 | Big-ip Access Policy Manager | ≥ 17.0.0 and ≤ 17.1.3≥ 17.5.0 and ≤ 17.5.1version 21.1.0 | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 9.3 | CVSS 4.0 | Critical | — | — | f5sirt@f5.com via NIST National Vulnerability Database |
| 9.3 | CVSS 4.0 | Critical | — | — | f5 via CVE Program (cve.org) e CISA ADP |
| 9.8 | CVSS 3.1 | Critical | 3.9 | 5.9 | f5sirt@f5.com via NIST National Vulnerability Database |
| 9.8 | CVSS 3.1 | Critical | — | — | GitHub, Inc. via GitHub Security Advisories |
| 9.8 | CVSS 3.1 | Critical | — | — | f5 via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: f5sirt@f5.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
CISA KEV details CISA
CISA lists a CVE once it has evidence of exploitation against real targets.
CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.
Public exploits, PoCs and detection templates
Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.
- watchtowrlabs/watchTowr-vs-f5-bigip-PreAuth-RCE-CVE-2026-94127 ★ 15 Sep 24, 2026
- CVE-2026-94127 ★ 0 Sep 23, 2026
Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 2.23%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
- Hunt retroactively in logs from before Sep 22, 2026 (KEV listing): exploitation may have started earlier.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · f5/big-ip
- SSVC assessment updated
- Record published
- Affected products added · f5/big-ip access policy manager
- CVSS changed · 9.8
- Source status changed · → Analyzed
- Added to CISA KEV (detected)
- Record created in this database
- CVE published
- Added to CISA KEV catalog
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 13, 2026 – Oct 13, 2026
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
4 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-42937 iControl REST and tmsh vulnerability May 13, 2026
- Medium CVE-2026-42919 F5 BIG-IP Appliance Mode Vulnerability May 13, 2026
- High CVE-2026-42920 BIG-IP DTLS Vulnerability May 13, 2026
- High CVE-2026-42930 Appliance mode iControl REST vulnerability May 13, 2026
- High CVE-2026-42924 BIG-IP iControl SOAP vulnerability May 13, 2026
- Medium CVE-2026-42781 BIG-IP FastL4 virtual server vulnerability May 13, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-94127 is "F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability", rated Critical. It affects BIG-IP (F5); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 9.8 describes technical severity. EPSS 2.23% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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