Bug ID 446664: Content length header leading whitespaces may cause false-positive

Last Modified: Apr 28, 2025

Affected Product(s):
BIG-IP ASM(all modules)

Known Affected Versions:
11.4.0, 11.4.1, 11.5.0, 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, 11.5.4, 11.5.4 HF1, 11.5.4 HF2, 11.5.4 HF3, 11.5.4 HF4, 11.5.5, 11.5.6, 11.5.7, 11.5.8, 11.5.9, 11.5.10

Fixed In:
11.6.0

Opened: Jan 29, 2014

Severity: 4-Minor

Symptoms

ASM blocks a request where the Content-Length header value has more than 20 leading spaces.

Impact

Web application requests are getting false positive blocks.

Conditions

-- ASM provisioned. -- ASM policy attached to a virtual server. -- 'Unparsable request content' sub-violation is enabled under 'HTTP protocol compliance checks' in the ASM policy.

Workaround

Use an iRule that strips leading spaces from the Content-Length header value.

Fix Information

This release fixes an issue that sometimes might have incorrectly triggered an unparseable request violation.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips