CVE-2026-31681netfilter: xt_multiport: validate range encoding in checkentry
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: xt_multiport: validate range encoding in checkentry ports_match_v1() treats any non-zero pflags entry as the start of a port range and unconditionally consumes the next ports[] element as the range end. The checkentry path currently validates protocol, flags and count, but it does not validate the range encoding itself. As a result, malformed rules can mark the last slot as a range start or place two range starts back to back, leaving ports_match_v1() to step past the last valid ports[] element while interpreting the rule. Reject malformed multiport v1 rules in checkentry by validating that each range start has a following element and that the following element is not itself marked as another range start.
- CVSS
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before 8c5bf8f5b478f569191c4a7982de7cd5f5f73c1a; from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before c9749f6232c845e31c21d4cc72200211df15d8a2; from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before b67d638cbee9975c765feb45c126e96ed11ec802; from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before 36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16; from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before aec14808271f2bf2b656de6ff12dfe73c5fd3b67; from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before 8368ce8eb01f0b91111d814703696e780d0ef12f; from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before 1e4baa853f1cc4227e04f52d6860524707cfb294; from a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 before ff64c5bfef12461df8450e0f50bb693b5269c720 | 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 SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name) | all versions | 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 6.6.136; from 6.7 before 6.12.83; from 6.13 before 6.18.24; from 6.19 before 6.19.14; 7.0; 7.0; 7.0; 7.0; and 3 more ranges | NVD |
References
- https://git.kernel.org/stable/c/8c5bf8f5b478f569191c4a7982de7cd5f5f73c1a
- https://git.kernel.org/stable/c/c9749f6232c845e31c21d4cc72200211df15d8a2
- https://git.kernel.org/stable/c/b67d638cbee9975c765feb45c126e96ed11ec802
- https://git.kernel.org/stable/c/36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16patch
- https://git.kernel.org/stable/c/aec14808271f2bf2b656de6ff12dfe73c5fd3b67patch
- https://git.kernel.org/stable/c/8368ce8eb01f0b91111d814703696e780d0ef12fpatch
- https://git.kernel.org/stable/c/1e4baa853f1cc4227e04f52d6860524707cfb294patch
- https://git.kernel.org/stable/c/ff64c5bfef12461df8450e0f50bb693b5269c720patch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
- https://cert-portal.siemens.com/productcert/html/ssa-784472.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.