Last Modified: Jul 18, 2026
Affected Product(s):
BIG-IP ASM
Known Affected Versions:
11.5.1, 11.5.1 hf1, 11.5.1 hf2, 11.5.1 hf3, 11.5.1 hf4, 11.5.1 hf5, 11.5.1 hf6, 11.5.1 hf7, 11.5.1 hf8, 11.5.1 hf9, 11.5.1 hf10, 11.5.1 hf11, 11.5.2, 11.5.2 hf1, 11.5.3, 11.5.3 hf1, 11.5.3 hf2
Fixed In:
11.6.0, 11.5.4
Opened: Jan 07, 2014 Severity: 3-Major
A customer has reported that they are seeing a non-trivial number of requests blocked with "HTTP Protocol compliance failed - Unparsable content length".
False positive of blocked requests upon content length headers with leading whitespaces.
The customer has a proxy before ASM that adds whitespaces before the content-length.
N/A
The system no longer blocks content length headers with leading whitespaces, because it is legal. The system used to issue the "HTTP protocol compliance failed" sub-violation: "Unparsable request content".