# CVE-2023-39193: Kernel: netfilter: xtables sctp out-of-bounds read in match_flags()

Status: published. Published: 2023-10-09. Updated: 2026-11-07.

A flaw was found in the Netfilter subsystem in the Linux kernel. The sctp_mt_check did not validate the flag_count field. This flaw allows a local privileged (CAP_NET_ADMIN) attacker to trigger an out-of-bounds read, leading to a crash or information disclosure.

## Remediation

- workaround: This flaw can be mitigated by preventing the affected `xt_sctp` kernel module from being loaded. For instructions on how to blacklist a kernel module, please see https://access.redhat.com/solutions/41278. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 8 (kernel-rt): ≥ 0:4.18.0-553.rt7.342.el8_10; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (kernel): ≥ 0:4.18.0-553.el8_10; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (kernel): ≥ 0:5.14.0-427.13.1.el9_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (kernel): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (kernel): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (kernel-rt): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (kernel-rt): Version range not reported. Source: CNA: redhat
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 TM MFP - GNU/Linux subsystem: ≥ 0; < V1.1 (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP

## Severity and prioritization

- CVSS 3.1: 6.1 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.42% as of 2026-11-06; percentile 36.90%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-125

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2024:2394 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:2950 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:3138 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2023-39193 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2226787 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://www.zerodayinitiative.com/advisories/ZDI-CAN-18866/ (CNA: redhat)

- https://access.redhat.com/errata/RHSA-2024:2394 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/errata/RHSA-2024:2950 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/errata/RHSA-2024:3138 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/security/cve/CVE-2023-39193 (ADP: CVE; vdb-entry, x_refsource_REDHAT, x_transferred)

- https://bugzilla.redhat.com/show_bug.cgi?id=2226787 (ADP: CVE; issue-tracking, x_refsource_REDHAT, x_transferred)

- https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html (ADP: CVE; x_transferred)

- https://www.zerodayinitiative.com/advisories/ZDI-CAN-18866/ (ADP: CVE; x_transferred)

- https://cert-portal.siemens.com/productcert/html/ssa-794697.html (ADP: siemens-SADP)

- https://cert-portal.siemens.com/productcert/html/ssa-398330.html (ADP: siemens-SADP)

- https://cert-portal.siemens.com/productcert/html/ssa-769027.html (ADP: siemens-SADP)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2023-39193; retrieved 2026-11-07; source updated 2026-11-07

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2023-39193; retrieved 2026-11-07; source updated Not reported

Revision: a95bcb27b8b79ffc22525b500ef09e633cc786ebe6dee031048cb2aa4c79021b

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