CVE-2026-94127: F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 22 Sep 2026, the same day the CVE record was published.
- How likely is exploitation in the next 30 days?
- 24.9%
EPSS score, percentile 97.9 of all scored records
- How severe?
- 9.3 Critical
CVSS v4.0 base score, given by the CNA
- What should I do?
Required action (CISA), due 25 Sep 2026: 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.
- Which versions are affected?
Affected: 21.1.0 up to, not including, Hotfix-BIGIP-21.1.0.2.0.30.22-ENG; 17.5.0 up to, not including, Hotfix-BIGIP-17.5.1.9.0.160.12-ENG; 17.1.0 up to, not including, Hotfix-BIGIP-17.1.3.5.0.41.14-ENG
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by 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.
CISA due date for this action: 25 September 2026.
Workaround (from the CVE record)
An iRule is available upon request. Open a ticket with F5 support to request this.
Advisories and patches
Linked from CISA's catalog entry
- https://my.f5.com/manage/s/article/K000162605
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-94127
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 21.1.0 up to, not including, Hotfix-BIGIP-21.1.0.2.0.30.22-ENG |
| Affected | 17.5.0 up to, not including, Hotfix-BIGIP-17.5.1.9.0.160.12-ENG |
| Affected | 17.1.0 up to, not including, Hotfix-BIGIP-17.1.3.5.0.41.14-ENG |
Versions not listed are: unknown.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
F5 BIG-IP APM contains a heap-based buffer overflow vulnerability when access policy and an OAuth profile are configured on a virtual server. This vulnerability could allow an unauthenticated attacker to perform remote code execution.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2026-94127 to its Known Exploited Vulnerabilities (KEV) catalog on 22 Sep 2026.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 25 Sep 2026.
- The CVE record was published on 22 Sep 2026, the same day it was added to KEV.
- The CVE record carries a CVSS v4.0 base score of 9.3 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 24.9% (percentile 97.9), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
BIG-IP APM OAuth 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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-122: Heap-based Buffer Overflow
Attack patterns (CAPEC)
- CAPEC-100: Overflow Buffers
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 22 Sep 2026 | CVE record published |
| 22 Sep 2026 | Added to CISA KEV |
| 23 Sep 2026 | CVE record last updated |
| 25 Sep 2026 | CISA due date for the required action |
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