{"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\/cs\/blog\/news\/obnarodovana-lpe-uyazvimost-cifswitch-v-linux-cifs-cifs-utils","title":{"rendered":"Byla zve\u0159ejn\u011bna LPE zranitelnost CIFSwitch v Linux CIFS\/cifs-utils","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Bezpe\u010dnostn\u00ed v\u00fdzkumn\u00edk <strong>Asim Manizada<\/strong> odhalil zranitelnost <strong>CIFSwitch<\/strong> \u2014 lok\u00e1ln\u00ed zv\u00fd\u0161en\u00ed opr\u00e1vn\u011bn\u00ed v j\u00e1d\u0159e Linux a u\u017eivatelsk\u00e9m bal\u00ed\u010dku <strong>cifs-utils<\/strong>. Probl\u00e9m se t\u00fdk\u00e1 cesty zpracov\u00e1n\u00ed <strong>CIFS\/SMB Kerberos\/SPNEGO upcall<\/strong>, tedy mechanismu, kter\u00fdm CIFS klient j\u00e1dra po\u017eaduje od u\u017eivatelsk\u00e9ho helpera data pro Kerberos autentifikaci p\u0159i p\u0159ipojov\u00e1n\u00ed SMB prost\u0159edk\u016f. Popis byl zve\u0159ejn\u011bn po uplynut\u00ed embarga linux-distros; identifik\u00e1tor CVE v dob\u011b publikace je\u0161t\u011b nebyl p\u0159id\u011blen.<\/p>\n<p><noindex><noindex><\/p>\n<p><a rel=\"nofollow\" href=\"https:\/\/almalinux.org\/blog\/2026-05-28-cifswitch\/\">Podstata zranitelnosti spo\u010d\u00edv\u00e1 v tom<\/a>, \u017ee nep\u0159 privileged u\u017eivatel mohl vyvolat request_key(&quot;cifs.spnego&quot;, &#8230;) a p\u0159edat podvodn\u00fd popis kl\u00ed\u010de. V norm\u00e1ln\u00edm sc\u00e9n\u00e1\u0159i by takov\u00fd \u0159et\u011bzec m\u011bl b\u00fdt vytvo\u0159en samotn\u00fdm CIFS klientem j\u00e1dra: obsahuje informace o serveru, UID, UID opr\u00e1vn\u011bn\u00ed, PID, c\u00edli upcall a dal\u0161\u00ed parametry. Av\u0161ak j\u00e1dro neov\u011b\u0159ovalo, \u017ee popis skute\u010dn\u011b poch\u00e1z\u00ed z CIFS pod syst\u00e9mu, a cifs.upcall, spu\u0161t\u011bn\u00fd jako root podle standardn\u00edho pravidla request-key, d\u016fv\u011b\u0159oval t\u011bmto pol\u00edm jako \u00fadaj\u016fm vytvo\u0159en\u00fdm j\u00e1drem.<\/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\">Zranitelnost nen\u00ed univerz\u00e1ln\u00ed<\/a> \u201ed\u00edrou v jak\u00e9mkoli Linuxu z krabice\u201c. Pro jej\u00ed zneu\u017eit\u00ed mus\u00ed splnit n\u011bkolik podm\u00ednek: p\u0159\u00edtomnost zraniteln\u00e9ho j\u00e1dra, nainstalovan\u00fd cifs-utils s pravidlem cifs.spnego, mo\u017enost pro neprivilegovan\u00e9 u\u017eivatele vytv\u00e1\u0159et user\/mount namespaces, a tak\u00e9 absenci blokace od SELinux, AppArmor nebo jin\u00fdch politik LSM. V ozn\u00e1men\u00ed na oss-security se zvl\u00e1\u0161\u0165 uv\u00e1d\u00ed, \u017ee na zraniteln\u00fdch syst\u00e9mech to poskytuje cestu od neprivilegovan\u00e9ho lok\u00e1ln\u00edho u\u017eivatele k vykon\u00e1n\u00ed k\u00f3du jako root.<\/p>\n<p><\/noindex><br \/>\n<noindex><\/p>\n<p>Technicky <a rel=\"nofollow\" href=\"https:\/\/blog.cloudlinux.com\/cifswitch-mitigation-and-kernel-update\">\u0159et\u011bzec se stav\u00ed kolem toho<\/a>, \u017ee cifs.upcall m\u016f\u017ee p\u0159ej\u00edt do jmenn\u00fdch prostor\u016f ur\u010den\u00fdch v fale\u0161n\u00e9m popisu a prov\u00e9st NSS dotaz a\u017e do kone\u010dn\u00e9ho sn\u00ed\u017een\u00ed opr\u00e1vn\u011bn\u00ed. V d\u016fsledku toho m\u016f\u017ee prost\u0159ed\u00ed ovl\u00e1dan\u00e9 \u00fato\u010dn\u00edkem ovlivnit na\u010d\u00edt\u00e1n\u00ed NSS modulu procesem root. Ve ve\u0159ejn\u00fdch popisech je zd\u016frazn\u011bno, \u017ee se jedn\u00e1 o logickou chybu na hranici j\u00e1dra a u\u017eivatelsk\u00e9ho prostoru, ne o klasickou zranitelnost pam\u011b\u0165ov\u00e9 korupce.<\/p>\n<p><\/noindex><\/p>\n<p>Oprava v j\u00e1d\u0159e se uk\u00e1zala jako mal\u00e1: pro typy kl\u00ed\u010d\u016f cifs.spnego byla p\u0159id\u00e1na kontrola, kter\u00e1 odm\u00edt\u00e1 popisy, kter\u00e9 nebyly vytvo\u0159eny samotn\u00fdm CIFS klientem s jeho soukrom\u00fdmi spnego_cred. Tento p\u0159\u00edstup zakr\u00fdv\u00e1 t\u0159\u00eddu \u00fatok\u016f bez povinn\u00fdch synchronn\u00edch zm\u011bn v cifs-utils, i kdy\u017e autor poznamen\u00e1v\u00e1, \u017ee dodate\u010dn\u00e9 pos\u00edlen\u00ed u\u017eivatelsk\u00e9ho prostoru je st\u00e1le \u017e\u00e1douc\u00ed.<\/p>\n<p><noindex><\/p>\n<p><a rel=\"nofollow\" href=\"https:\/\/almalinux.org\/blog\/2026-05-28-cifswitch\/\">AlmaLinux ozn\u00e1mil<\/a>, \u017ee z\u00e1kladn\u00ed logika je p\u0159\u00edtomna ve v\u0161ech podporovan\u00fdch verz\u00edch AlmaLinux, a AlmaLinux 8, 9, 10 a Kitten 10 jsou pova\u017eov\u00e1ny za ohro\u017een\u00e9 v p\u0159\u00edpad\u011b, \u017ee je nainstalov\u00e1no cifs-utils. Opraven\u00e1 j\u00e1dra byla p\u0159ipravena v testing-repozit\u00e1\u0159\u00edch: pro AlmaLinux 9 je uveden bal\u00ed\u010dek kernel-5.14.0-687.5.4.el9_8 nebo nov\u011bj\u0161\u00ed, pro AlmaLinux 10 \u2014 kernel-6.12.0-211.7.4.el10_2 nebo nov\u011bj\u0161\u00ed.<\/p>\n<p><\/noindex><\/p>\n<p>Jako do\u010dasn\u00e1 opat\u0159en\u00ed p\u0159ed instalac\u00ed opraven\u00e9ho j\u00e1dra se doporu\u010duje odstranit cifs-utils, pokud nen\u00ed na syst\u00e9mu pou\u017e\u00edv\u00e1n SMB\/CIFS klient, zak\u00e1zat na\u010d\u00edt\u00e1n\u00ed modulu cifs, p\u0159epsat pravidlo cifs.spnego v request-key nebo deaktivovat nepriviligovan\u00e9 u\u017eivatelsk\u00e9 namespaces. Tato obch\u00e1zej\u00edc\u00ed opat\u0159en\u00ed mohou naru\u0161it Kerberos autentizaci pro CIFS mont\u00e1\u017ee, proto je t\u0159eba je aplikovat opatrn\u011b na serverech, kde se skute\u010dn\u011b vyu\u017e\u00edvaj\u00ed Kerberos-authentizovan\u00e9 SMB sd\u00edlen\u00e9 slo\u017eky.<\/p>\n<p>CIFSwitch je zaj\u00edmav\u00fd tak\u00e9 v kontextu objevov\u00e1n\u00ed: autor ji popisuje jako v\u00fdsledek p\u00e1tr\u00e1n\u00ed po v\u00edcestup\u0148ov\u00fdch \u0159et\u011bzc\u00edch pomoc\u00ed LLM a grafov\u00e9ho zobrazen\u00ed vztah\u016f mezi objekty bezpe\u010dnosti. Ale praktick\u00fd z\u00e1v\u011br pro administr\u00e1tory je docela prost\u00fd: zkontrolovat p\u0159\u00edtomnost cifs-utils, stav u\u017eivatelsk\u00fdch namespaces a aktualizace j\u00e1dra, zejm\u00e9na na syst\u00e9mech, kde jsou m\u00edstn\u00ed u\u017eivatel\u00e9 nebo kontejnerov\u00e9 skripty s roz\u0161\u00ed\u0159en\u00fdmi mo\u017enostmi namespaces.<\/p>\n<p>Zdroj: <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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