Bug 2492853 (CVE-2026-53270)

Summary: CVE-2026-53270 kernel: ipvs: clear the svc scheduler ptr early on edit
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, 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 IP Virtual Server (IPVS) component. During the `ip_vs_edit_service()` operation, the `svc->scheduler` pointer is cleared too late when unbinding an old scheduler. This improper handling allows packets to access previously freed scheduler data, leading to a use-after-free vulnerability. This can result in system instability or a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-06-25 10:09:08 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ipvs: clear the svc scheduler ptr early on edit

ip_vs_edit_service() while unbinding the old scheduler clears
the svc->scheduler ptr after the scheduler module initiates
RCU callbacks. This can cause packets to use the old
scheduler at the time when svc->sched_data is already freed
after RCU grace period.

Fix it by clearing the ptr early in ip_vs_unbind_scheduler(),
before the done_service method schedules any RCU callbacks.

Also, if the new scheduler fails to initialize when replacing
the old scheduler, try to restore the old scheduler while still
returning the error code.
Comment 1 Mauro Matteo Cascella 2026-06-25 16:19:36 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062518-CVE-2026-53270-0981@gregkh/T