Last Modified: Sep 13, 2023
Affected Product(s):
BIG-IP GTM, LTM
Known Affected Versions:
11.4.1, 11.6.0, 12.0.0, 12.0.0 HF1, 12.1.0 HF1, 12.0.0 HF2, 12.1.0 HF2, 12.1.1 HF1, 12.1.1 HF2, 12.1.2 HF1, 12.1.2 HF2
Fixed In:
12.1.0, 12.0.0 HF3, 11.6.1, 11.5.4 HF2, 11.4.1 HF10
Opened: Oct 29, 2015 Severity: 2-Critical
A resolver sending a query with a small EDNS0 UDP buffer limit can lead to packet truncation. These response packets are flagged as truncated in the header, but the OPT record might be cut/missing leading some resolvers to consider the packet malformed.
Some resolvers regard OPT-less truncated packets as malformed and cease follow-up requests via TCP or a larger EDNS0 UDP limit.
Primarily via dynamic settings such as iRules on DNS_RESPONSE events adding new records, or DNSSEC record signing with responses over UDP.
none
Truncated DNSSEC or iRule DNS packets are RFC-compliant.