Bug 2455331 (CVE-2026-31407)

Summary: CVE-2026-31407 kernel: netfilter: conntrack: add missing netlink policy validations
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 conntrack subsystem. Missing netlink policy validations allow a local attacker to provide a specially crafted input, leading to an out-of-bounds read. This vulnerability can result in information disclosure from kernel memory or potentially cause a denial of service.
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Description OSIDB Bzimport 2026-04-06 09:01:12 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: conntrack: add missing netlink policy validations

Hyunwoo Kim reports out-of-bounds access in sctp and ctnetlink.

These attributes are used by the kernel without any validation.
Extend the netlink policies accordingly.

Quoting the reporter:
  nlattr_to_sctp() assigns the user-supplied CTA_PROTOINFO_SCTP_STATE
  value directly to ct->proto.sctp.state without checking that it is
  within the valid range. [..]

  and: ... with exp->dir = 100, the access at
  ct->master->tuplehash[100] reads 5600 bytes past the start of a
  320-byte nf_conn object, causing a slab-out-of-bounds read confirmed by
  UBSAN.
Comment 1 Keith Grant 2026-04-06 11:46:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026040628-CVE-2026-31407-6abd@gregkh/T