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

March 27, 2026 15:00 /HIGH

CISA KEV vulnerabilitycvecisa-kevactively-exploited

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

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CVE-2025-53521 — F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.

Please adhere to F5’s guidelines to assess exposure and mitigate risks. Check for signs of potential compromise on all internet accessible F5 products affected by this vulnerability. For more information please see: https://my.f5.com/manage/s/article/K000156741 ; https://my.f5.com/manage/s/article/K000160486 ; https://my.f5.com/manage/s/article/K11438344 ; https://nvd.nist.gov/vuln/detail/CVE-2025-53521

What This Means For You

CISA has confirmed active exploitation — immediate patching required.
Added to CISA KEV catalog — federal agencies must remediate by 2026-03-30.

Indicators of Compromise

ID	Type	Indicator
CVE-2025-53521	Buffer Overflow	F5 BIG-IP APM, stack-based buffer overflow vulnerability, potential for RCE
CVE-2025-53521	RCE	F5 BIG-IP APM, stack-based buffer overflow vulnerability allowing remote code execution

Source & Attribution

Source Platform	CISA
Channel	CISA KEV
Channel ID	cisa-kev
Message ID	202553521
Published	March 27, 2026 at 15:00 UTC
Original Link	Please adhere to F5’s guidelines to assess exposure and m...

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