Bug 2454851 (CVE-2026-23456)

Summary: CVE-2026-23456 kernel: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
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 H.323 connection tracking module. A remote attacker could exploit this vulnerability by sending a specially crafted H.323/RAS (H.323 Registration, Admission, and Status) packet. The system's processing of these packets could lead to an out-of-bounds read of 1-4 bytes, potentially causing information disclosure or a denial of service (DoS).
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Description OSIDB Bzimport 2026-04-03 16:04:14 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case

In decode_int(), the CONS case calls get_bits(bs, 2) to read a length
value, then calls get_uint(bs, len) without checking that len bytes
remain in the buffer. The existing boundary check only validates the
2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint()
reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte
slab-out-of-bounds read.

Add a boundary check for len bytes after get_bits() and before
get_uint().
Comment 1 Jon Moroney 2026-04-03 17:40:08 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026040318-CVE-2026-23456-7da2@gregkh/T