Skip to content
Fencer Intel
critical 9.8

CVE-2025-53521 kev in the critical feed json

BigIP APM Vulnerability

published last yr. modified last mo. also EUVD-2025-34630

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2026-03-27
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

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.

Patch / fix

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.

  • F5 BIG-IP 15.1.10.8, 16.1.6.1, 17.1.3, 17.5.1.3

Is CVE-2025-53521 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Timeline

  1. Published
  2. Added to CISA KEV
  3. CISA SSVC: exploitation active
  4. CISA patch deadline

Known exploited

Added
7mo ago
Patch by
2026-03-30 (7mo ago)
Ransomware
Not known
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, product
F5, BIG-IP
CISA name
F5 BIG-IP Stack-Based Buffer Overflow Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
7mo ago

Exploit prediction

2.30% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 4.0 9.3 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
CNA 4.0 9.3 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/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:X

Affected products

  • F5 BIG-IP

Classification

Weakness
  • CWE-121 Stack-based Buffer Overflow

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.