What’s Vulnerable › Vulnerabilities

CVE-2026-89476: sctp: fix stream->outcnt underflow on duplicate RECONF responses

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-11 · updated 2026-10-19

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.

Affected products

• Linux kernel: 4.12 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/041f7df5a929d3e7435dd8387e8ea17f2d412b7d
• https://git.kernel.org/stable/c/092acd3c55a4077b00489064615d8d2d898daf91
• https://git.kernel.org/stable/c/2d867663c563e8009257b9edf9c8ec75d9bbf19a
• https://git.kernel.org/stable/c/3faf13aff243ca9f78d08b1a2956ef5a6fc77b6e
• https://git.kernel.org/stable/c/59f61c39cb99ee1737bd742a20094fe5653389bb
• https://git.kernel.org/stable/c/793519e343867ee9a3e84f6cac07f81f2aec7b5d
• https://git.kernel.org/stable/c/8320cbd81bc21a1ca6ebdf70ad610ebc5ef1bd68
• https://git.kernel.org/stable/c/d02a5794c3deedcb8476d017fcee2b7aaedab2e1

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