Bug 2540500 (CVE-2026-93288)

Summary: CVE-2026-93288 kernel: netfilter: nfnetlink_log: wait for rcu grace period before freeing pernet state
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
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   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's netfilter subsystem. When a network namespace is dismantled, the packet logging component frees memory without waiting for ongoing logging operations to complete, resulting in a use-after-free condition. A local attacker could exploit this flaw during network traffic processing to cause a system crash, leading to a Denial of Service (DoS), or potentially execute arbitrary code.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-24 17:02:13 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nfnetlink_log: wait for rcu grace period before freeing pernet state

sashiko reports: "nfnl_log_net_exit() calls nf_log_unset(), which
clears the logger pointer without an RCU grace period.  Immediately after,
ops_free_list() frees the per-net state while concurrent packets might
still be executing nf_log_packet() under rcu_read_lock()."

Clear the pointer via .pre_exit to make sure rcu readers have completed
before pernet storage is free'd.  The change in nf_log_syslog.c is only
done for consistency: it doesn't use pernet data.
Comment 1 Mauro Matteo Cascella 2026-09-28 08:59:15 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93288.mbox
Comment 3 Jon Orris 2026-10-07 20:28:45 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:76738 https://access.redhat.com/errata/RHSA-2026:76738
Comment 4 Jon Orris 2026-10-08 09:50:37 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:76739 https://access.redhat.com/errata/RHSA-2026:76739
Comment 5 Jon Orris 2026-10-20 03:42:47 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:85774 https://access.redhat.com/errata/RHSA-2026:85774
Comment 6 Jon Orris 2026-10-20 03:52:03 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:85773 https://access.redhat.com/errata/RHSA-2026:85773