Bug 2521365 (CVE-2026-74624)

Summary: CVE-2026-74624 kernel: netfilter: nf_conntrack: defer invalid log until after unlock
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: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's netfilter component. Specifically, the TCP and SCTP connection tracking (conntrack) paths can attempt to log invalid packets while a critical lock is still held. If invalid logging is routed to nfnetlink_log and conntrack export is enabled, this can lead to a deadlock, resulting in a Denial of Service (DoS) for the system.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-08-22 15:41:56 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conntrack: defer invalid log until after unlock

TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock
is still held.

When invalid logging is routed to nfnetlink_log and conntrack export is
enabled, the log path can re-enter conntrack netlink glue and dump the
same conntrack again. Protocol attribute dumping may take ct->lock, so
logging while holding that lock can deadlock.

Defer the TCP invalid logs by storing only the minimal log context while
ct->lock is held and emitting the log after unlocking. Also make the TCP
timeout-lowering invalid path return whether a log is needed, then emit
that log after unlocking.

Do the same for the SCTP invalid state-transition log that can be reached
while ct->lock is held.

Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers
that log invalid conntracks while holding ct->lock are caught outside TCP
and SCTP as well.
Comment 1 gkamathe 2026-08-24 07:35:21 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082220-CVE-2026-74624-2bd0@gregkh/T