CVE-2026-23455netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.
- CVSS
- 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 5e35941d990123f155b02d5663e51a24f816b6f3 before 2121f5fbe88daff0f1fc5bc47d359426c74b86b0; from 5e35941d990123f155b02d5663e51a24f816b6f3 before 65fa92f79677858b14b9e4b7275f26639afe2710; from 5e35941d990123f155b02d5663e51a24f816b6f3 before 495e97af9e7249ee02b72bb1d0848a6efc3700f4; from 5e35941d990123f155b02d5663e51a24f816b6f3 before f5e4f4e4cdb75ec36802059a94195a31f193da60; from 5e35941d990123f155b02d5663e51a24f816b6f3 before 633e8f87dad32263f6a57dccdb873f042c062111; from 5e35941d990123f155b02d5663e51a24f816b6f3 before 9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8; from 5e35941d990123f155b02d5663e51a24f816b6f3 before b652b05d51003ac074b912684f9ec7486231717b; from 5e35941d990123f155b02d5663e51a24f816b6f3 before f173d0f4c0f689173f8cdac79991043a4a89bf66 | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 2.6.17 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.20; from 6.19 before 6.19.10; 7.0; and 3 more ranges | NVD |
References
- https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0patch
- https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710patch
- https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4patch
- https://git.kernel.org/stable/c/f5e4f4e4cdb75ec36802059a94195a31f193da60patch
- https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111patch
- https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8patch
- https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717bpatch
- https://git.kernel.org/stable/c/f173d0f4c0f689173f8cdac79991043a4a89bf66patch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.