{"id":181809,"date":"2026-05-30T14:48:10","date_gmt":"2026-05-30T12:48:10","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/obnarodovana-lpe-uyazvimost-cifswitch-v-linux-cifs-cifs-utils"},"modified":"2026-05-30T14:48:10","modified_gmt":"2026-05-30T12:48:10","slug":"obnarodovana-lpe-uyazvimost-cifswitch-v-linux-cifs-cifs-utils","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/obnarodovana-lpe-uyazvimost-cifswitch-v-linux-cifs-cifs-utils","title":{"rendered":"LPE-s\u00e5rbarhed i CIFSwitch offentliggjort i Linux CIFS\/cifs-utils","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Sikkerhedsforsker <strong>Asim Manizada<\/strong> har afsl\u00f8ret en s\u00e5rbarhed <strong>CIFSwitch<\/strong> \u2014 lokal forh\u00f8jelse af privilegier i kombination med Linux-kernen og et brugerpakke <strong>cifs-utils<\/strong>. Problemet p\u00e5virker behandlingsstien for <strong>CIFS\/SMB Kerberos\/SPNEGO upcall<\/strong>, alts\u00e5 mekanismen, hvormed CIFS-kernklienten anmoder om data til Kerberos-godkendelse fra brugerhelper'en, n\u00e5r SMB-ressourcer monteres. Beskrivelsen blev offentliggjort efter udl\u00f8bet af embargoen fra linux-distros; CVE-identifikatoren var endnu ikke tildelt p\u00e5 offentligg\u00f8relsestidspunktet.<\/p>\n<p><noindex><noindex><\/p>\n<p><a rel=\"nofollow\" href=\"https:\/\/almalinux.org\/blog\/2026-05-28-cifswitch\/\">Essensen af s\u00e5rbarheden er,<\/a>, som en ikke-privilegeret bruger kunne kalde request_key(&quot;cifs.spnego&quot;, &#8230;) og videregive en falsk n\u00f8glebeskrivelse. I et normalt scenarie skulle en s\u00e5dan streng genereres af selve CIFS-klienten i kernen: den indeholder oplysninger om serveren, UID, credential UID, PID, m\u00e5let for upcall og andre parametre. Men kernen kontrollerede ikke, om beskrivelsen virkelig kom fra CIFS-subsystemet, og cifs.upcall, der k\u00f8rer som root gennem den standard-foresp\u00f8rgselsn\u00f8gle, stolede p\u00e5 disse felter som data genereret af kernen.<\/p>\n<p><\/noindex><\/noindex><\/p>\n<p><noindex><\/p>\n<p><a rel=\"nofollow\" href=\"https:\/\/www.openwall.com\/lists\/oss-security\/2026\/05\/28\/2\">S\u00e5rbarheden er ikke universel<\/a> \u00abet hul i enhver Linux fra start\u00bb. For at udnytte det skal flere betingelser v\u00e6re opfyldt: en s\u00e5rbar kerne, installeret cifs-utils med reglen cifs.spnego, mulighed for ikke-privilegerede brugere at oprette user\/mount namespaces, samt frav\u00e6ret af blokering fra SELinux, AppArmor eller anden LSM-politik. Det blev n\u00e6vnt i en meddelelse p\u00e5 oss-security, at p\u00e5 s\u00e5rbare systemer giver dette en vej fra en ikke-privilegeret lokal bruger til udf\u00f8relse af kode som root.<\/p>\n<p><\/noindex><br \/>\n<noindex><\/p>\n<p>Teknisk set <a rel=\"nofollow\" href=\"https:\/\/blog.cloudlinux.com\/cifswitch-mitigation-and-kernel-update\">er k\u00e6den bygget op omkring det,<\/a>, at cifs.upcall kan bev\u00e6ge sig ind i de navneomr\u00e5der, der er angivet i den falske beskrivelse, og udf\u00f8re NSS-foresp\u00f8rgsel indtil endelig tilbagef\u00f8rsel af privilegier. Som resultat kan et attacker-kontrolleret milj\u00f8 p\u00e5virke indl\u00e6sningen af NSS-modulet fra root-processen. I offentlige beskrivelser understreges det, at dette netop er en logisk fejl p\u00e5 gr\u00e6nsen mellem kernen og brugerens rum, og ikke en klassisk memory corruption-s\u00e5rbarhed.<\/p>\n<p><\/noindex><\/p>\n<p>Reparationen i kernen viste sig at v\u00e6re beskeden: for n\u00f8gletyperne cifs.spnego blev der tilf\u00f8jet en kontrol, der afviser beskrivelser, der ikke blev skabt af CIFS-klienten selv med dens private spnego_cred. Denne tilgang lukker klassen af angreb uden n\u00f8dvendige synkrone \u00e6ndringer i cifs-utils, selvom forfatteren bem\u00e6rker, at yderligere styrkelse af brugerens rum stadig er \u00f8nskeligt.<\/p>\n<p><noindex><\/p>\n<p><a rel=\"nofollow\" href=\"https:\/\/almalinux.org\/blog\/2026-05-28-cifswitch\/\">AlmaLinux rapporterede<\/a>, at den grundl\u00e6ggende logik er til stede i alle underst\u00f8ttede versioner af AlmaLinux, og at AlmaLinux 8, 9, 10 og Kitten 10 betragtes som ber\u00f8rte, n\u00e5r cifs-utils er installeret. De patchede kerner er blevet forberedt i testing-repositorierne: for AlmaLinux 9 er den angivne pakke kernel-5.14.0-687.5.4.el9_8 eller nyere, og for AlmaLinux 10 \u2014 kernel-6.12.0-211.7.4.el10_2 eller nyere.<\/p>\n<p><\/noindex><\/p>\n<p>Som en midlertidig l\u00f8sning, indtil den rettede kerne er installeret, foresl\u00e5s det at fjerne cifs-utils, hvis SMB\/CIFS-klienten ikke anvendes p\u00e5 systemet, at forbyde indl\u00e6sning af cifs-modulet, at overstyre cifs.spnego-reglen i request-key, eller at deaktivere de ikke-privilegerede user namespaces. Disse workarounds kan bryde Kerberos-godkendelse for CIFS-montering, s\u00e5 p\u00e5 servere, hvor Kerberos-godkendte SMB-deltagelser faktisk bruges, skal de anvendes med forsigtighed.<\/p>\n<p>CIFSwitch er ogs\u00e5 interessant i konteksten af opdagelse: forfatteren beskriver det som resultatet af s\u00f8gning efter flerstegs k\u00e6der ved hj\u00e6lp af LLM og grafiske repr\u00e6sentationer af forbindelser mellem sikkerhedsobjekter. Men den praktiske konklusion for administratorer er ganske jordn\u00e6r: at tjekke for cifs-utils, state of user namespaces og kernel-opdateringer, is\u00e6r p\u00e5 systemer med lokale brugere eller container-scripts med avancerede namespace-muligheder.<\/p>\n<p>Kilde: <a \ncontent=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.linux.org.ru\/news\/security\/18305995\">linux.org.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0418\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 Asim Manizada \u0440\u0430\u0441\u043a\u0440\u044b\u043b \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c CIFSwitch \u2014 \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u0435 \u043f\u043e\u0432\u044b\u0448\u0435\u043d\u0438\u0435 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0439 \u0432 \u0441\u0432\u044f\u0437\u043a\u0435 \u044f\u0434\u0440\u0430 Linux \u0438 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044c\u0441\u043a\u043e\u0433\u043e \u043f\u0430\u043a\u0435\u0442\u0430 cifs-utils. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0437\u0430\u0442\u0440\u0430\u0433\u0438\u0432\u0430\u0435\u0442 \u043f\u0443\u0442\u044c \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0438 CIFS\/SMB Kerberos\/SPNEGO upcall, \u0442\u043e \u0435\u0441\u0442\u044c \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c, \u0447\u0435\u0440\u0435\u0437 \u043a\u043e\u0442\u043e\u0440\u044b\u0439 CIFS-\u043a\u043b\u0438\u0435\u043d\u0442 \u044f\u0434\u0440\u0430 \u0437\u0430\u043f\u0440\u0430\u0448\u0438\u0432\u0430\u0435\u0442 \u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044c\u0441\u043a\u043e\u0433\u043e helper\u2019\u0430 \u0434\u0430\u043d\u043d\u044b\u0435 \u0434\u043b\u044f Kerberos-\u0430\u0443\u0442\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0446\u0438\u0438 \u043f\u0440\u0438 \u043c\u043e\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0438 SMB-\u0440\u0435\u0441\u0443\u0440\u0441\u043e\u0432. \u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u043e \u043f\u043e\u0441\u043b\u0435 \u0438\u0441\u0442\u0435\u0447\u0435\u043d\u0438\u044f \u044d\u043c\u0431\u0430\u0440\u0433\u043e linux-distros; \u0438\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440 CVE \u043d\u0430 \u043c\u043e\u043c\u0435\u043d\u0442 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438 \u0435\u0449\u0451 [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-181809","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.3 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u0418\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 Asim Manizada \u0440\u0430\u0441\u043a\u0440\u044b\u043b \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c CIFSwitch \u2014 \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u0435 \u043f\u043e\u0432\u044b\u0448\u0435\u043d\u0438\u0435 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0439 \u0432 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