CVEs / CVE-2025-53521
CVE-2025-53521: F5 BIG-IP Stack-Based Buffer Overflow Vulnerability
- Known exploited in the CISA KEV catalog since 27 Mar 2026
- critical 9.3 CVSS 4.0 (from the CNA)
- EPSS 2.29% chance of exploitation in the next 30 days, higher than 83% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.
Description
When a BIG-IP APM access policy is configured on a virtual server, specific malicious traffic can lead to Remote Code Execution (RCE). Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| F5 BIG-IP | from 17.5.0, before 17.5.1.3 | 17.5.1.3 |
| F5 BIG-IP | from 17.1.0, before 17.1.3 | 17.1.3 |
| F5 BIG-IP | from 16.1.0, before 16.1.6.1 | 16.1.6.1 |
| F5 BIG-IP | from 15.1.0, before 15.1.10.8 | 15.1.10.8 |
Exploitation
| In CISA KEV since | 27 Mar 2026 |
|---|---|
| Due date for US federal agencies | 30 Mar 2026 |
| Used in ransomware campaigns | Unknown |
| Required action | Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. |
Severity
| CVSS 4.0 | 9.3 criticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XScored by the CNA ([email protected]) |
|---|---|
| Weakness | CWE-121 |
References
- CVE-2025-53521 on NVD
- CVE-2025-53521 in the CISA KEV catalog
- https://my.f5.com/manage/s/article/K000156741 (cited by CISA)
- https://my.f5.com/manage/s/article/K000160486 (cited by CISA)
- https://my.f5.com/manage/s/article/K11438344 (cited by CISA)
- https://my.f5.com/manage/s/article/K000156741 Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53521 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.