CVE-2026-72021
HighCVSS 8.2Exploitation Probability (EPSS)
Low risk45th percentile - higher than 45% of all known CVEs
Summary
In the Linux kernel, in the IPVS subsystem, the set_sctp_state() function incorrectly calculates the offset for IPv6 SCTP packets with extension headers, leading to incorrect state machine behavior. The fix uses the parsed transport offset passed from ip_vs_set_state() to correctly read the SCTP header.
Risk Assessment
Incorrect SCTP load balancing, potentially leading to improper traffic forwarding and connection reliability issues.
Recommendation
It is recommended to update the Linux kernel to a patched version and test IPVS configurations with IPv6 SCTP traffic.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ipvs: use parsed transport offset in SCTP state lookup set_sctp_state() reads the SCTP chunk header again in order to drive the IPVS SCTP state table. For IPv6 it computes the offset with sizeof(struct ipv6hdr), while the surrounding IPVS code uses iph.len from ip_vs_fill_iph_skb(), where ipv6_find_hdr() has already skipped extension headers and found the real transport header. This makes the state machine read from the wrong offset for IPv6 SCTP packets that carry extension headers. For example, an INIT packet with an 8-byte destination options header can be scheduled correctly by sctp_conn_schedule(), but set_sctp_state() reads the first byte of the SCTP verification tag as a DATA chunk type. The connection then moves from NONE to ESTABLISHED instead of INIT1, gets the longer established timeout, and updates the active/inactive destination counters incorrectly. This happens even though the SCTP handshake has not completed. Use the parsed transport offset passed down from ip_vs_set_state() for the SCTP chunk-header lookup. For IPv4 and IPv6 packets without extension headers this preserves the existing offset.