CVE-2026-89476 sctp: fix stream->outcnt underflow on duplicate RECONF responses
An attacker can cause an integer underflow in the Linux kernel SCTP implementation via duplicate RECONF responses, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89476?
CVE-2026-89476 is a high-severity vulnerability in Linux, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-89476?
How do I fix CVE-2026-89476?
Apply the vendor's patch.
Is CVE-2026-89476 being exploited?
There is no known exploitation of CVE-2026-89476 in the wild and no public exploit code.
Sources
Also known as AZL-100701, BELL-CVE-2026-89476, DEBIAN-CVE-2026-89476, GHSA-p69r-6fx2-qv4w, UBUNTU-CVE-2026-89476.