CVE-2026-89476

Received Received - Intake

SCTP Stream Outcnt Underflow in Linux Kernel

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: sctp: fix stream->outcnt underflow on duplicate RECONF responses A cached RECONF chunk may contain more than one request parameter. A duplicate response can therefore find and process the same ADD_OUT request again while another parameter is still outstanding, rolling back outcnt twice and possibly underflowing it. Track outstanding request types as bits and clear each bit after its first response. Later responses for the same request are then ignored.

CVSS Scores

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Meta Information

Published

2026-09-11

Last Modified

2026-09-11

Generated

2026-09-12

AI Q&A

2026-09-12

EPSS Evaluated

N/A

NVD

CVE-2026-89476

EUVD

EUVD-2026-76382

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves an underflow issue in the SCTP protocol's stream handling. When duplicate RECONF responses are processed, the system incorrectly rolls back the count of outstanding requests twice, potentially causing it to underflow. The fix involves tracking request types as bits and clearing each after its first response to ignore later duplicates.

Impact Analysis

This vulnerability could lead to system crashes or instability in systems using the Linux kernel with SCTP protocol enabled. An attacker might exploit this to cause denial-of-service conditions by triggering the underflow, disrupting network services.

Mitigation Strategies

Update the Linux kernel to the patched version where this vulnerability is resolved. Monitor vendor advisories for kernel updates and apply them promptly.

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