9.8

CVE-2025-53521: F5 BIG-IP Stack-Based Buffer Overflow Vulnerability

CVSS: 9.8v3.1CriticalKEVAnalyzed
Published 15-10-2025Last modified 31-03-2026
Open JSON

Vulnerability summary

CVE-2025-53521 is a critical (CVSS 9.8) Stack-based Buffer Overflow vulnerability in F5 BIG-IP. It is known to be exploited: CISA lists it, first on 27-03-2026. EPSS estimates a 2.30% chance of exploitation in the next 30 days, higher than 83.1% of scored vulnerabilities.

Overall risk
85/100
0100
Critical · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
2.30%
0%100%
Low · 0.00 pp in 30 days
KEVListedCISA
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 15-10-2025
    PublishedVulnerability first disclosed.
  2. 27-03-2026
    Added to CISA KEVF5 BIG-IP Stack-Based Buffer Overflow Vulnerability
  3. 30-03-2026
    CISA remediation dueApply mitigations per vendor instructions.
  4. 31-03-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

2.30%

Chance of exploitation in the next 30 days

Percentile

83%

Versus all other CVEs

30-day change

0.00 pp

From 2.30% on 21-09-2026

21-09-202621-10-2026
EPSS score
2.30%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
27-03-2026
Federal due date
30-03-2026

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. my.f5.com/manage/s/article/K000160486 my.f5.com/manage/s/article/K11438344 nvd.nist.gov/vuln/detail/CVE-2025-53521

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

F52 products
  • big-ip≥ 17.5.0, < 17.5.1.3 | ≥ 17.1.0, < 17.1.3 | ≥ 16.1.0, < 16.1.6.1 | ≥ 15.1.0, < 15.1.10.8
  • big-ip_access_policy_manager≥ 15.1.0, < 15.1.10.8 | ≥ 16.1.0, < 16.1.6.1 | ≥ 17.1.0, < 17.1.3 | ≥ 17.5.0, < 17.5.1.3

1 vendor · 2 products

References

2 links