CVE-2026-68300
Received Received - Intake

SCTP Authentication Bypass in Linux Kernel

Vulnerability report for CVE-2026-68300, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

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.

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves incorrect authentication handling in the SCTP protocol. The function sctp_auth_chunk_verify() incorrectly returns true when the auth_chunk field is NULL, skipping authentication checks. This can happen if skb_clone() fails or if no AUTH chunk precedes a COOKIE-ECHO message. The fix requires verifying authentication requirements even when auth_chunk is NULL.

Detection Guidance

This vulnerability affects the Linux kernel's SCTP protocol handling. Detection requires checking kernel logs for SCTP-related errors or crashes, particularly during chunk processing. Monitor for failed authentication attempts or malformed SCTP packets. Use commands like 'dmesg | grep sctp' or 'journalctl -k | grep sctp' to inspect kernel logs for anomalies.

Impact Analysis

This vulnerability could allow an attacker to bypass authentication checks in SCTP connections, potentially leading to unauthorized access or data manipulation. It affects new connections where the kernel fails to properly validate authentication, especially in cases of resource exhaustion or malformed packets.

Mitigation Strategies

Apply the latest Linux kernel patches to address the SCTP authentication flaw. Update to a kernel version containing the fix for sctp_auth_chunk_verify(). If immediate patching is not possible, consider disabling SCTP protocol usage temporarily or restrict network exposure to trusted sources.

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