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Review reviewCritical

CVE-2026-43011

Linux Linux, SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP

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:...

CVSS
9.8
EPSS
0.59%
44.9% percentile
CISA KEV
Not listed
Published
2026.05.02
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.59%
Technical severityCVSS 9.8

Vulnerability overview

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:...

Affected product and versions

Product
Linux Linux, SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
Affected versions
>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5d0aa038a90b30c9bedde0c41c1fdcd98ecb16e9, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3f5e3005984645bf5bd129c6b13149879580b1fb, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f782dd382203b2a8c4552a628431b7de65a19a7b, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 524371398d8463ea7e101fce2cbf3915645d1730, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < fa1dbc93530b34fab0da9862426fe9c918c74dc0, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c87dd137c0dad07cc55f98181ff380b0c23d2878, >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < d10a26aa4d072320530e6968ef945c8c575edf61, >= 2.6.12, >= V3.1.6, >= V3.1.5, >= 2.6.12.1 < 5.10.253, >= 5.11 < 5.15.203, >= 5.16 < 6.1.168, >= 6.2 < 6.6.134, >= 6.7 < 6.12.81, >= 6.13 < 6.18.22, >= 6.19 < 6.19.12, 2.6.12, 7.0
Fixed versions
5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-415