Expired Pointer Dereference Affecting kernel-rt-debug package, versions *
Threat Intelligence
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Test your applications- Snyk IDSNYK-CENTOS10-KERNELRTDEBUG-17776762
- published2 Jul 2026
- disclosed1 Jul 2026
Introduced: 1 Jul 2026
NewCVE-2026-53349 (opens in a new tab)How to fix?
There is no fixed version for Centos:10 kernel-rt-debug.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug package and not the kernel-rt-debug package as distributed by Centos.
See How to fix? for Centos:10 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack: destroy stale expectfn expectations on unregister
NAT helpers such as nf_nat_h323 store a raw pointer to module text in exp->expectfn (e.g. ip_nat_q931_expect). nf_ct_helper_expectfn_unregister() only unlinks the callback descriptor and never walks the expectation table, so an expectation pending at module removal survives with a dangling exp->expectfn into freed module text.
When the expected connection arrives, init_conntrack() invokes exp->expectfn(), now a stale pointer into the unloaded module. Reproduced on a KASAN build by loading the H.323 helpers, creating a Q.931 expectation, unloading nf_nat_h323, then connecting to the expected port:
Oops: int3: 0000 [#1] SMP KASAN NOPTI RIP: 0010:0xffffffffa06102d1 init_conntrack.isra.0 (net/netfilter/nf_conntrack_core.c:1862) nf_conntrack_in (net/netfilter/nf_conntrack_core.c:2049) ipv4_conntrack_local (net/netfilter/nf_conntrack_proto.c:223) nf_hook_slow (net/netfilter/core.c:619) __ip_local_out (net/ipv4/ip_output.c:120) __tcp_transmit_skb (net/ipv4/tcp_output.c:1715) tcp_connect (net/ipv4/tcp_output.c:4374) tcp_v4_connect (net/ipv4/tcp_ipv4.c:345) __sys_connect (net/socket.c:2167) Modules linked in: nf_conntrack_h323 [last unloaded: nf_nat_h323]
Reaching the dangling state requires CAP_SYS_MODULE in the initial user namespace to remove a NAT helper that still has live expectations, so this is a robustness fix; leaving an expectation pointing at freed text is wrong regardless.
Add nf_ct_helper_expectfn_destroy(), which walks the expectation table and drops every expectation whose ->expectfn matches the descriptor being torn down. Call it from each NAT helper's exit path after the existing RCU grace period, so no expectation outlives the code it points at and no extra synchronize_rcu() is introduced. With the fix, the same reproducer runs to completion without the Oops.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=2495929
- https://access.redhat.com/security/cve/CVE-2026-53349
- https://git.kernel.org/stable/c/29d8cc44bbdf7b83a1929912214afe6643c1b4f1
- https://git.kernel.org/stable/c/9d017671dcfcec23321fb7962dea624f9e71ddb1
- https://git.kernel.org/stable/c/bf8c0b5dd203be94c2ad50e264cec19267c6bd39
- https://git.kernel.org/stable/c/c3009418f9fa1dcb3eb86f4d8c92583537b5faa3
- https://git.kernel.org/stable/c/f92c90a2a3e6ff6f9f7fe88fde9004b4ca8f956d
- https://git.kernel.org/stable/c/fbfde85308b99938a6092c48753214d190ece48d