High severity · published Apr 3, 2026
CVE-2026-23456
netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
8.2
CVSS
0.5%
EPSS
No
On KEV
Description
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().
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
2.6.17 before 5.10.253; 5.11 before 5.15.203; 5.16 before 6.1.167; 6.2 before 6.6.130; 6.7 before 6.12.78; 6.13 before 6.18.20; +5 more · source: NVD
LI
Linux · Linux
5e35941d990123f155b02d5663e51a24f816b6f3 before a2cd54b9348e485d338b3c132338a4410c99afaf; 5e35941d990123f155b02d5663e51a24f816b6f3 before c95dc674ebf01ecfb40388b6facfc89b81fed3b7; 5e35941d990123f155b02d5663e51a24f816b6f3 before 41b417ff73a24b2c68134992cc44c88db27f482d; 5e35941d990123f155b02d5663e51a24f816b6f3 before 52235bf88159a1ef16434ab49e47e99c8a09ab20; 5e35941d990123f155b02d5663e51a24f816b6f3 before 774a434f8c9c8602a976b2536f65d0172a07f4d2; 5e35941d990123f155b02d5663e51a24f816b6f3 before 6bce72daeccca9aa1746e92d6c3d4784e71f2ebb; +3 more · source: vendor
SS
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.6; V3.1.5; V3.1.7; V3.1.6; V3.1.5; V3.1.7 · source: CISA
SS
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP · Siemens
V3.1.6; V3.1.5; V3.1.7; V3.1.6; V3.1.5; V3.1.7 · source: CISA
SS
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.6; V3.1.5; V3.1.7 · source: CISA