CVE-2026-72021: Linux Vulnerability (CVSS 8.2)

Description

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.

Metrics

CVSS 3.1

8.2/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS Probability

0.21%

11.6th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 2906f66a5682e5670a5eefe991843689b8d8563f, < d2b8b1557ec07ea1bb5dddbceaf4dfe63d388e27; >= 2906f66a5682e5670a5eefe991843689b8d8563f, < 9f94573ab962a9e81954b755da016fa3cd2f5039; >= 2906f66a5682e5670a5eefe991843689b8d8563f, < 290e9e8389b556efc603522e28bd1543846aa336; >= 2906f66a5682e5670a5eefe991843689b8d8563f, < 9cb5ac594ca76d3a71803b23b74c835b0721e628; >= 2906f66a5682e5670a5eefe991843689b8d8563f, < a4a2d2e483d79cc2ad3a170674cf159644acf22b; >= 2906f66a5682e5670a5eefe991843689b8d8563f, < 247d055504dcc852e539b9f7f30d19f9741474bf; >= 2906f66a5682e5670a5eefe991843689b8d8563f, < e5d0bb8871668f20de8f3c94b5ae3f372346bc6e; >= 2906f66a5682e5670a5eefe991843689b8d8563f, < 2f75c0faa3361b28e36cc0512b3299e163e25789
Linux	Linux	2.6.34

References

Timeline

Published: Aug 15, 2026
Last Modified: Aug 17, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-72021?

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.

How severe is CVE-2026-72021?

CVE-2026-72021 has a CVSS score of 8.2/10 (HIGH severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2026-72021?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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