Last Modified: Apr 17, 2026
Affected Product(s):
BIG-IP TMOS
Known Affected Versions:
17.1.0, 17.1.0.1, 17.1.0.2, 17.1.0.3, 17.1.1, 17.1.1.1, 17.1.1.2, 17.1.1.3, 17.1.1.4, 17.1.2, 17.1.2.1, 17.1.2.2, 17.1.3, 17.1.3.1, 17.5.1, 17.5.1.2, 17.5.1.3, 17.5.1.4, 17.5.1.5, 21.0.0, 21.0.0.1
Opened: Mar 09, 2026 Severity: 3-Major
With a SIP profile and iRule routing by string match, a valid 200 OK with a folded (multi-line) Accept header is not forwarded, but it forwards correctly if the Accept header is on a single line.
When a SIP profile is applied and Content-Length is present, SIP messages with folded (multi-line) headers are silently dropped, causing call setup failures, missed responses, or other signaling disruptions.
Virtual Server: UDP port 5060 (SIP) Profiles: SIP profile, UDP profile (default settings) Pool: At least one pool member iRule: Attached to the virtual server Send a SIP 200 OK response to the BIG-IP with a folded Accept header.
Use the flattened Accept Header in payload: Accept: application/sdp, application/isup, multipart/mixed, application/dtmf
None