Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

Forum Discussion

Anthony_Epron's avatar
Anthony_Epron
Icon for Nimbostratus rankNimbostratus
Jun 16, 2020

Irule to make HTTP request size compliant with header

Hello,   I need to implement in F5 is a possibility to reject an HTTP request in case the size of the request is not corresponding to the Content-Length of the header.   I cannot use ASM for ...
irules
LTM
security
PeteWhite's avatar
PeteWhite
Icon for Employee rankEmployee
Jun 20, 2020

what you are trying to do will work with GET but you may wish to consider POST, where you will have to use HTTP::collect and use HTTP::payload length.

For use with GET, you can simply use string length:

when HTTP_REQUEST {
  if { [expr {  [string length [HTTP::request]] eq ne expr [HTTP::header "Content-Length"]} {
    reject
  }
 }