The Linux kernel contains a flaw in the SCTP inqueue parser where it accepts chunks with declared lengths shorter than the required four‑byte header. When an ASCONF chunk is processed under the association’s SCTP‑AUTH policy, the flawed function can repeatedly return the same malformed chunk, causing the receive softirq to lock up and drain the system’s watchdog health checks. The impact is a denial of service that can be forced remotely by any SCTP peer that can establish an association with the vulnerable kernel. Affected systems are Linux distributions running kernels that have the CONFIG_IP_SCTP option enabled together with SCTP’s address‑configuration and authentication features (net.sctp.addip_enable=1, net.sctp.auth_enable=1). The vulnerability is specific to the kernel itself, so all installations that include the SCTP stack and are compiled with the mentioned options are potentially impacted. No particular kernel release number is listed, but the fix is referenced as commit f967455fb2a5. The known exploitability is limited to remote peers that can initiate SCTP associations. While no EPSS score is available and the vulnerability is not listed in CISA’s KEV catalog, the ciphertext description indicates that a zero‑length ASCONF packet can trigger the lockup in a KVM guest. The attack does not require application credentials or an AUTH key and therefore is relatively easy to execute against a properly configured kernel.

Linux kernel installations that have the SCTP stack enabled (CONFIG_IP_SCTP) together with the address‑configuration and authentication options turned on. Any distribution running a built kernel in this configuration is potentially affected, but no specific vendor or version details are provided.

The flaw enables a remote denial‑of‑service condition by causing softirq lockups. Because the attack does not require privileged credentials or special configuration beyond the enabled SCTP features, the likelihood of exploitation in environments that expose SCTP is considered moderate. The vulnerability is not yet in the CISA KEV catalog and no EPSS score is published, but the described reproduction shows realistic impact in virtualized guests. Consequently, administrators should assess whether SCTP is required in their environment and apply the patch as soon as possible.