# CVE-2023-42755: Kernel: rsvp: out-of-bounds read in rsvp_classify() Status: published. Published: 2023-10-05. Updated: 2026-11-07. A flaw was found in the IPv4 Resource Reservation Protocol (RSVP) classifier in the Linux kernel. The xprt pointer may go beyond the linear part of the skb, leading to an out-of-bounds read in the `rsvp_classify` function. This issue may allow a local user to crash the system and cause a denial of service. ## Remediation - workaround: This flaw can be mitigated by preventing the affected `cls_rsvp` 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) - fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: secalert@redhat.com) — https://bugzilla.redhat.com/show_bug.cgi?id=2239847 - fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: secalert@redhat.com) — https://seclists.org/oss-sec/2023/q3/229 - fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: af854a3a-2127-422b-91ae-364da2661108) — https://bugzilla.redhat.com/show_bug.cgi?id=2239847 - fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: af854a3a-2127-422b-91ae-364da2661108) — https://seclists.org/oss-sec/2023/q3/229 ## 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 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): 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 ## NVD configuration conditions Affected CPE matches depend on the following AND/OR and negation conditions: ```json [ { "negate": false, "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.3", "vulnerable": true } ], "negate": false, "operator": "OR" } ], "operator": "OR" }, { "negate": false, "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*", "vulnerable": true } ], "negate": false, "operator": "OR" } ], "operator": "OR" }, { "negate": false, "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*", "vulnerable": true } ], "negate": false, "operator": "OR" } ], "operator": "OR" } ] ``` ## Severity and prioritization - CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H; source: CNA: redhat - CVSS 3.1: 5.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: NVD: nvd@nist.gov - CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H; source: NVD: secalert@redhat.com - CISA KEV: No listing in collected sources - EPSS: 0.40% as of 2026-11-06; percentile 34.64% - SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP - Weaknesses: CWE-125 ## Exploit evidence - exploit: https://seclists.org/oss-sec/2023/q3/229 (secalert@redhat.com) - exploit: https://seclists.org/oss-sec/2023/q3/229 (af854a3a-2127-422b-91ae-364da2661108) ## References - 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-2023-42755 (CNA: redhat; vdb-entry, x_refsource_REDHAT) - https://bugzilla.redhat.com/show_bug.cgi?id=2239847 (CNA: redhat; issue-tracking, x_refsource_REDHAT) - https://seclists.org/oss-sec/2023/q3/229 (CNA: redhat) - 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-2023-42755 (ADP: CVE; vdb-entry, x_refsource_REDHAT, x_transferred) - https://bugzilla.redhat.com/show_bug.cgi?id=2239847 (ADP: CVE; issue-tracking, x_refsource_REDHAT, x_transferred) - https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html (ADP: CVE; x_transferred) - https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html (ADP: CVE; x_transferred) - https://seclists.org/oss-sec/2023/q3/229 (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://access.redhat.com/errata/RHSA-2024:2950 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2024:3138 (secalert@redhat.com) - https://access.redhat.com/security/cve/CVE-2023-42755 (secalert@redhat.com; Third Party Advisory) - https://bugzilla.redhat.com/show_bug.cgi?id=2239847 (secalert@redhat.com; Issue Tracking, Patch, Third Party Advisory) - https://seclists.org/oss-sec/2023/q3/229 (secalert@redhat.com; Exploit, Mailing List, Patch, Third Party Advisory) - https://access.redhat.com/errata/RHSA-2024:2950 (af854a3a-2127-422b-91ae-364da2661108) - https://access.redhat.com/errata/RHSA-2024:3138 (af854a3a-2127-422b-91ae-364da2661108) - https://access.redhat.com/security/cve/CVE-2023-42755 (af854a3a-2127-422b-91ae-364da2661108; Third Party Advisory) - https://bugzilla.redhat.com/show_bug.cgi?id=2239847 (af854a3a-2127-422b-91ae-364da2661108; Issue Tracking, Patch, Third Party Advisory) - https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html (af854a3a-2127-422b-91ae-364da2661108) - https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html (af854a3a-2127-422b-91ae-364da2661108) - https://seclists.org/oss-sec/2023/q3/229 (af854a3a-2127-422b-91ae-364da2661108; Exploit, Mailing List, Patch, Third Party Advisory) - https://cert-portal.siemens.com/productcert/html/ssa-398330.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e) - https://cert-portal.siemens.com/productcert/html/ssa-794697.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e) ## Provenance - CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2023-42755; retrieved 2026-11-07; source updated 2026-11-07 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-42755; retrieved 2026-11-07; source updated 2026-11-07 - FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2023-42755; retrieved 2026-11-07; source updated Not reported Revision: a5773d7de9621cb082423d3aa42cbcd097ef1e7a948da61ade790b7402b99fed Canonical: https://y2.dev/cve/CVE-2023-42755 ## Agent and API access Public CVE pages, Markdown, and JSON are free to read without an account or API key. - Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end. - WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers. - Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}. - Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer . Setup: https://y2.dev/docs/api/create-key. - x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402. - OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json. Collected public records only. Check source status for coverage and freshness.