Bug 2548390 (CVE-2026-98379)

Summary: CVE-2026-98379 kernel: netfilter: ip6t_rpfilter: reject routes without inet6_dev
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 netfilter subsystem. An unprivileged local user can cause a Denial of Service (DoS) by triggering a system crash through a null pointer dereference (an attempt to access invalid memory). This issue occurs during IPv6 reverse-path filtering when the kernel evaluates routes that lack associated interface device data following network configuration changes. By generating traffic that prompts lookups on these incomplete routes, a local attacker can force a kernel panic.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-10-09 08:01:27 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: ip6t_rpfilter: reject routes without inet6_dev

ip6_route_lookup() can return an error-free route whose rt6i_idev is
NULL. Lowering an external nexthop device's MTU below IPV6_MIN_MTU tears
down its inet6_dev while fib6_ifdown() leaves routes using nexthop objects
in the FIB. An unprivileged user can construct this state with rtnetlink
in a private user and network namespace, then trigger a NULL dereference
through an IPv6 rpfilter lookup:

  Oops: general protection fault, probably for non-canonical address
  0xdffffc0000000000
  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
  RIP: rpfilter_mt (net/ipv6/netfilter/ip6t_rpfilter.c:75)
  Call Trace:
  ip6t_do_table (net/ipv6/netfilter/ip6_tables.c:316)
  nf_hook_slow (net/netfilter/core.c:619)
  ipv6_rcv (net/ipv6/ip6_input.c:351)
  __netif_receive_skb_one_core (net/core/dev.c:6216)
  process_backlog (net/core/dev.c:6680)
  __napi_poll (net/core/dev.c:7739)
  net_rx_action (net/core/dev.c:7959)
  handle_softirqs (kernel/softirq.c:622)
  do_softirq.part.0 (kernel/softirq.c:523)
  __local_bh_enable_ip (kernel/softirq.c:450)
  __dev_queue_xmit (net/core/dev.c:4913)
  packet_sendmsg (net/packet/af_packet.c:3139)
  __sys_sendto (net/socket.c:2252)
  __x64_sys_sendto (net/socket.c:2259)
  do_syscall_64 (arch/x86/entry/syscall_64.c:94)
  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
  Kernel panic - not syncing: Fatal exception in interrupt

Reject routes without an inet6_dev immediately after lookup. Such routes
are not eligible for reverse-path filtering, and the check protects all
later rt6i_idev dereferences.
Comment 1 gkamathe 2026-10-10 15:34:49 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98379.mbox