Bug 2555197 (CVE-2026-98846)

Summary: CVE-2026-98846 kernel: sctp: check RCV_SHUTDOWN after the sendmsg connect wait
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) subsystem. A race condition can occur when an SCTP socket is shut down concurrently while waiting for a connection, causing an association structure to be freed while still in use. A local user could exploit this flaw to trigger a use-after-free condition, resulting in a Denial of Service (DoS) via a system crash or potential privilege escalation.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-18 16:01:22 UTC 
In the Linux kernel, the following vulnerability has been resolved:

sctp: check RCV_SHUTDOWN after the sendmsg connect wait

sctp_wait_for_connect() drops the socket lock while it sleeps. An
out-of-the-blue ABORT can then be processed from the socket backlog and
unlink the association. If a concurrent shutdown(fd, SHUT_RD) sets
RCV_SHUTDOWN, the waiter breaks with err == 0 before checking
asoc->base.dead. Its final sctp_association_put() can then free the
association, leaving sctp_sendmsg_to_asoc() to continue with a dangling
pointer.

Check RCV_SHUTDOWN along with the wait error in sctp_sendmsg_to_asoc()
before using the association again. The check only accesses the socket,
so it needs no additional association reference. Return the existing
-ESRCH so that sctp_sendmsg() skips freeing a new association that may
already have been destroyed.

Keep sctp_wait_for_connect() unchanged to preserve its behavior for the
connect() caller.
Comment 1 Mauro Matteo Cascella 2026-10-23 22:06:40 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98846.mbox