CVE-2025-53521: F5 BIG-IP Stack-Based Buffer Overflow Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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.
Description quoted from the CVE record (assigned by f5, published 2025-10-15).
Weakness: CWE-121 Stack-based Buffer Overflow
How it can be exploited
Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.
- On CISA KEV since
- 2026-03-27
- US federal deadline
- 2026-03-30
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: CNNVD-202510-2159, EUVD-2025-34630, GHSA-j3cp-7wh4-9f6c
Exploit Observer has no public exploit code that names this CVE or one of its aliases.
Vulnerability databases and vendor advisories (5)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2025-34630
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-j3cp-7wh4-9f6c
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-53521
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53521
- Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202510-2159
3 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.023
some chance of attack soon - VEDAS
- 0.521
some exploit evidence - On CISA KEV
- Yes, since 2026-03-27
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| F5 BIG-IP | from 17.5.0 before 17.5.1.3 from 17.1.0 before 17.1.3 from 16.1.0 before 16.1.6.1 from 15.1.0 before 15.1.10.8 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: f5 big-ip_access_policy_manager.
How to fix it
Fixed versions stated in the CVE record: 17.5.1.3, 17.1.3, 16.1.6.1, 15.1.10.8.
CISA 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.
Vendor guidance:
- https://my.f5.com/manage/s/article/K000156741 (vendor-advisory)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
References
Vendor advisories and patches
- https://my.f5.com/manage/s/article/K000156741 (vendor-advisory)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53521 (government-resource)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.