CVE-2026-68300Authentication bypass in Linux kernel SCTP
In the Linux kernel, the following vulnerability has been resolved: sctp: auth: verify auth requirement when auth_chunk is NULL sctp_auth_chunk_verify() returns true unconditionally when chunk->auth_chunk is NULL, silently skipping authentication. This is incorrect when: 1. skb_clone() failed in the BH receive path, leaving auth_chunk NULL. In sctp_endpoint_bh_rcv() asoc is NULL for new connections, so the early sctp_auth_recv_cid() check cannot catch this. 2. No AUTH chunk precedes COOKIE-ECHO, so skb_clone() is never called and auth_chunk remains NULL. Fix by checking sctp_auth_recv_cid() when auth_chunk is NULL: if authentication is required, return false to drop the chunk; otherwise continue normally.
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A critical vulnerability in the Linux kernel SCTP implementation allows attackers to bypass authentication requirements during connection establishment. This could lead to unauthorized network access on systems where the SCTP protocol is active.
Relevant roles
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HEPSS
Technical description
In the Linux kernel, the following vulnerability has been resolved: sctp: auth: verify auth requirement when auth_chunk is NULL sctp_auth_chunk_verify() returns true unconditionally when chunk->auth_chunk is NULL, silently skipping authentication. This is incorrect when: 1. skb_clone() failed in the BH receive path, leaving auth_chunk NULL. In sctp_endpoint_bh_rcv() asoc is NULL for new connections, so the early sctp_auth_recv_cid() check cannot catch this. 2. No AUTH chunk precedes COOKIE-ECHO, so skb_clone() is never called and auth_chunk remains NULL. Fix by checking sctp_auth_recv_cid() when auth_chunk is NULL: if authentication is required, return false to drop the chunk; otherwise continue normally.
References
- https://git.kernel.org/stable/c/18957373920caf5cdaf5cf32e5d1d7a99ca7700a
- https://git.kernel.org/stable/c/28c5fdce9dd955d2baf5e28987819b6d7cfaf646
- https://git.kernel.org/stable/c/83f5031f2a6a49d696eb4cc0898345d12f9c6451
- https://git.kernel.org/stable/c/8e04823c120b376ef7dab14b60ebf6823aa16c14
- https://git.kernel.org/stable/c/ec2e157fc9678a9bc411305a25aec3fd337d7efb