Medium 5.5Published Jun 25, 2026

CVE-2026-53218netfilter: nft_exthdr: fix register tracking for F_PRESENT flag

Updated under an hour ago (Oct 28, 2026, 3:00 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag nft_exthdr_init() passes user-controlled priv->len to nft_parse_register_store(), which marks that many bytes in the register bitmap as initialized. However, when NFT_EXTHDR_F_PRESENT is set, the eval paths write only 1 byte (nft_reg_store8) or 4 bytes (*dest = 0 on TCP/DCCP error path). When len > 4, registers beyond the first are never written, retaining uninitialized stack data from nft_regs. Bail out if userspace requests too much data when F_PRESENT is set.

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 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before 8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6; from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before 19748967d59c31d24d21d40b728570788310b237; from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before 46fc15a044e9938e7ea77786fb37edd2cd74f031; from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before cd513e43b4b2bd1de39e2367bc4261c699a8652f; from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before 67b27434c43b68a97becda98c9f0c8cf6cba2134; from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before 78069a6d8bc86c9e036eb82c2af4a19cc1871a53; from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265; from c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 before 772cecf198da732faebb5dcfc46d66a505be8495	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 4.11 before 5.10.259; from 5.11 before 5.15.210; from 5.16 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; from 6.19 before 7.0.13; 7.1; and 6 more ranges	NVD

References

References

https://git.kernel.org/stable/c/8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6	patch
https://git.kernel.org/stable/c/19748967d59c31d24d21d40b728570788310b237	patch
https://git.kernel.org/stable/c/46fc15a044e9938e7ea77786fb37edd2cd74f031	patch
https://git.kernel.org/stable/c/cd513e43b4b2bd1de39e2367bc4261c699a8652f	patch
https://git.kernel.org/stable/c/67b27434c43b68a97becda98c9f0c8cf6cba2134	patch
https://git.kernel.org/stable/c/78069a6d8bc86c9e036eb82c2af4a19cc1871a53	patch
https://git.kernel.org/stable/c/f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265	patch
https://git.kernel.org/stable/c/772cecf198da732faebb5dcfc46d66a505be8495	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-457936.html
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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.