Critical 9.8Published May 1, 2026

CVE-2026-43011net/x25: Fix potential double free of skb

Updated under an hour ago (Oct 28, 2026, 3:50 AM ET)

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It affects Linux and 4 other products. Add what you run to find out whether that includes you.

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: net/x25: Fix potential double free of skb When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at line 48 and returns 1 (error). This error propagates back through the call chain: x25_queue_rx_frame returns 1 | v x25_state3_machine receives the return value 1 and takes the else branch at line 278, setting queued=0 and returning 0 | v x25_process_rx_frame returns queued=0 | v x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb) again This would free the same skb twice. Looking at x25_backlog_rcv: net/x25/x25_in.c:x25_backlog_rcv() { ... queued = x25_process_rx_frame(sk, skb); ... if (!queued) kfree_skb(skb); }

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-415
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 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 5d0aa038a90b30c9bedde0c41c1fdcd98ecb16e9; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 3f5e3005984645bf5bd129c6b13149879580b1fb; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before f782dd382203b2a8c4552a628431b7de65a19a7b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 524371398d8463ea7e101fce2cbf3915645d1730; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before fa1dbc93530b34fab0da9862426fe9c918c74dc0; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before c87dd137c0dad07cc55f98181ff380b0c23d2878; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before d10a26aa4d072320530e6968ef945c8c575edf61	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 2.6.12.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.134; from 6.7 before 6.12.81; from 6.13 before 6.18.22; from 6.19 before 6.19.12; 2.6.12; and 10 more ranges	NVD

References

References

https://git.kernel.org/stable/c/5d0aa038a90b30c9bedde0c41c1fdcd98ecb16e9	patch
https://git.kernel.org/stable/c/3f5e3005984645bf5bd129c6b13149879580b1fb	patch
https://git.kernel.org/stable/c/f782dd382203b2a8c4552a628431b7de65a19a7b	patch
https://git.kernel.org/stable/c/143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1	patch
https://git.kernel.org/stable/c/524371398d8463ea7e101fce2cbf3915645d1730	patch
https://git.kernel.org/stable/c/fa1dbc93530b34fab0da9862426fe9c918c74dc0	patch
https://git.kernel.org/stable/c/c87dd137c0dad07cc55f98181ff380b0c23d2878	patch
https://git.kernel.org/stable/c/d10a26aa4d072320530e6968ef945c8c575edf61	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-082556.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.