Spole\u010dnost Qualys odhalila zranitelnost (CVE-2026-3888) v organizaci pr\u00e1ce mezi snap-confine a systemd-tmpfiles v Ubuntu, kter\u00e1 umo\u017e\u0148uje neprivilegovan\u00e9mu u\u017eivateli z\u00edskat root p\u0159\u00edstup k syst\u00e9mu. Probl\u00e9m se projevuje v Ubuntu v konfiguraci ve v\u00fdchoz\u00edm nastaven\u00ed od verze 24.04. Ve verz\u00edch Ubuntu 16.04-22.04 m\u016f\u017ee b\u00fdt zranitelnost zneu\u017eita v nestandardn\u00edch konfigurac\u00edch, kter\u00e9 napodobuj\u00ed chov\u00e1n\u00ed nov\u011bj\u0161\u00edch verz\u00ed distribuce. Oprava je pro Ubuntu k dispozici v\u010derej\u0161\u00edm aktualizac\u00edm bal\u00ed\u010dku snapd. V snapd byla probl\u00e9m odstran\u011bn v aktualizaci 2.75. <\/p>\n
Zranitelnost vznik\u00e1 z d\u016fvodu nespr\u00e1vn\u00e9 interakce utility snap-confine a systemd-tmpfiles, kter\u00e9 se prov\u00e1d\u011bj\u00ed s vyvy\u0161ovan\u00fdmi privilegii. Utility snap-confine vytv\u00e1\u0159\u00ed sandboxov\u00e9 prost\u0159ed\u00ed pro spu\u0161t\u011bn\u00ed snap aplikace, zat\u00edmco systemd-tmpfiles prov\u00e1d\u00ed automatick\u00e9 \u010di\u0161t\u011bn\u00ed do\u010dasn\u00fdch soubor\u016f a adres\u00e1\u0159\u016f. V\u00fdchoz\u00ed nastaven\u00ed utility systemd-tmpfiles je nakonfigurov\u00e1no tak, aby odstra\u0148ovalo v\u0161echny star\u00e9 soubory a adres\u00e1\u0159e v \/tmp, co\u017e m\u016f\u017ee b\u00fdt vyu\u017eito \u00fato\u010dn\u00edkem k nahrazen\u00ed adres\u00e1\u0159e \/tmp\/.snap v okam\u017eiku po jeho odstran\u011bn\u00ed utility systemd-tmpfiles, ale p\u0159ed jeho op\u011btovn\u00fdm vytvo\u0159en\u00edm p\u0159\u00edkazem snap-confine. <\/p>\n
\u00datok spo\u010d\u00edv\u00e1 v \u010dek\u00e1n\u00ed na spu\u0161t\u011bn\u00ed procesu \u010di\u0161t\u011bn\u00ed do\u010dasn\u00fdch soubor\u016f, nahrazen\u00ed adres\u00e1\u0159e \/tmp\/.snap po jeho odstran\u011bn\u00ed a um\u00edst\u011bn\u00ed modifikovan\u00e9 kopie knihoven \/tmp\/.snap\/usr\/lib\/x86_64-linux-gnu.exchange. \u00dato\u010dn\u00edk m\u016f\u017ee pot\u0159ebovat n\u011bkolik dn\u00ed \u010dek\u00e1n\u00ed na spu\u0161t\u011bn\u00ed systemd-tmpfiles, proto\u017ee v Ubuntu 24.04 se proces \u010di\u0161t\u011bn\u00ed spou\u0161t\u00ed jednou za 10 dn\u00ed, a v nov\u011bj\u0161\u00edch verz\u00edch - jednou za 30 dn\u00ed. Po nahrazen\u00ed adres\u00e1\u0159e \u00fato\u010dn\u00edk dos\u00e1hne inicializace nov\u00e9ho sandboxov\u00e9ho prost\u0159ed\u00ed pomoc\u00ed snap-confine. <\/p>\n
B\u011bhem formov\u00e1n\u00ed obsahu sandboxov\u00e9ho prost\u0159ed\u00ed v do\u010dasn\u00e9m adres\u00e1\u0159i \/tmp\/.snap \u010dek\u00e1 \u00fato\u010dn\u00edk na spr\u00e1vn\u00fd okam\u017eik a p\u0159ejmenov\u00e1v\u00e1 \/tmp\/.snap\/usr\/lib\/x86_64-linux-gnu.exchange na \/tmp\/.snap\/usr\/lib\/x86_64-linux-gnu, \u010d\u00edm\u017e nahrazuje knihovny a zaji\u0161\u0165uje jejich bind-mont\u00e1\u017e s pr\u00e1vy root. T\u00edmto zp\u016fsobem \u00fato\u010dn\u00edk z\u00edsk\u00e1v\u00e1 kontrolu nad sd\u00edlen\u00fdmi knihovnami a loaderem ld.so, spou\u0161t\u011bn\u00fdmi v sandboxov\u00e9m prost\u0159ed\u00ed snap, a m\u016f\u017ee dos\u00e1hnout vykon\u00e1n\u00ed libovoln\u00e9ho k\u00f3du s pr\u00e1vy root prost\u0159ednictv\u00edm spu\u0161t\u011bn\u00ed jak\u00e9hokoli suid programu, ve kter\u00e9m se pou\u017e\u00edv\u00e1 dynamick\u00e9 propojov\u00e1n\u00ed. <\/p>\n
M\u00edt root p\u0159\u00edstup v sandboxov\u00e9m prost\u0159ed\u00ed izolovan\u00e9m pomoc\u00ed AppArmor a filtrem syst\u00e9mov\u00fdch vol\u00e1n\u00ed zalo\u017een\u00fdm na seccompu, \u00fato\u010dn\u00edk m\u016f\u017ee zkop\u00edrovat \/bin\/bash do adres\u00e1\u0159e \/var\/snap\/$SNAP\/common a p\u0159i\u0159adit mu pr\u00e1va \u201e04755\u201c (suid root). I kdy\u017e jsou pr\u00e1va zm\u011bn\u011bna uvnit\u0159 sandboxov\u00e9ho prost\u0159ed\u00ed, soubor s modifikovan\u00fdmi pr\u00e1vy je dostupn\u00fd i v hlavn\u00edm syst\u00e9mu, tak\u017ee pro z\u00edsk\u00e1n\u00ed \u00fapln\u00e9ho root p\u0159\u00edstupu sta\u010d\u00ed spustit \/var\/snap\/\/common\/bash b\u011b\u017en\u00fdm nep\u0159id\u011blen\u00fdm u\u017eivatelem z b\u011b\u017en\u00e9ho syst\u00e9mov\u00e9ho prost\u0159ed\u00ed. <\/p>\n
Sou\u010dasn\u011b byla odhalena zranitelnost v n\u00e1stroji uutils coreutils (Rust Coreutils), analogii bal\u00ed\u010dku GNU Coreutils, napsan\u00e9ho v jazyce Rust. Zranitelnost umo\u017e\u0148uje nep\u0159 privilegeovan\u00e9mu u\u017eivateli z\u00edskat pr\u00e1va root v syst\u00e9mu. Probl\u00e9m byl odhalen v procesu recenzov\u00e1n\u00ed zm\u011bn v Ubuntu 25.10 a byl obch\u016fzen p\u0159ed uveden\u00edm Ubuntu 25.10 dod\u00e1n\u00edm \/usr\/bin\/gnurm m\u00edsto uutils rm. V bal\u00ed\u010dku uutils byla chyba opravena ve vyd\u00e1n\u00ed uutils coreutils 0.3.0, ani\u017e by byla zaznamen\u00e1na v seznamu zm\u011bn o odstran\u011bn\u00ed zranitelnosti (bylo uvedeno, \u017ee v rm, du, chmod a chgrp byl implementov\u00e1n bezpe\u010dn\u00fd zp\u016fsob obch\u00e1zen\u00ed cest). <\/p>\n
Probl\u00e9m je zp\u016fsoben z\u00e1vodem ve utilit\u011b \u201erm\u201c, kter\u00e1 umo\u017e\u0148uje lok\u00e1ln\u00edmu u\u017eivateli nahradit obsah adres\u00e1\u0159e symbolick\u00fdm odkazem b\u011bhem odstra\u0148ov\u00e1n\u00ed souboru pod kontrolou u\u017eivatele procesem \u201erm\u201c s pr\u00e1vy root. Mimo jin\u00e9 m\u016f\u017ee b\u00fdt zranitelnost zneu\u017eita p\u0159i ka\u017edodenn\u00edm spu\u0161t\u011bn\u00ed z cron skriptu \/etc\/cron.daily\/apport, kter\u00fd se spou\u0161t\u00ed s pr\u00e1vy root a rekurzivn\u011b odstra\u0148uje obsah adres\u00e1\u0159e \/var\/crash, kter\u00fd je zapisovateln\u00fd v\u0161em u\u017eivatel\u016fm v syst\u00e9mu. <\/p>\n
P\u0159i rekurzivn\u00edm odstra\u0148ov\u00e1n\u00ed adres\u00e1\u0159\u016f utilita rm nejprve kontroluje v\u0161echny adres\u00e1\u0159e a pot\u00e9 je postupn\u011b odstra\u0148uje v opa\u010dn\u00e9m po\u0159ad\u00ed, p\u0159i\u010dem\u017e vol\u00e1 funkci rmdir(). Pokud se poda\u0159\u00ed nahradit rodi\u010dovsk\u00fd adres\u00e1\u0159 symbolick\u00fdm odkazem ihned po kontrole tohoto adres\u00e1\u0159e, ale p\u0159ed kontrolou jeho vno\u0159en\u00fdch podadres\u00e1\u0159\u016f, operace povede k odstran\u011bn\u00ed adres\u00e1\u0159e, na kter\u00fd odkazuje symbolick\u00fd odkaz. T\u00edmto zp\u016fsobem lze dos\u00e1hnout nejen odstran\u011bn\u00ed jak\u00e9hokoli souboru v syst\u00e9mu, ale tak\u00e9 zv\u00fd\u0161en\u00ed privilegi\u00ed pomoc\u00ed odstran\u011bn\u00ed adres\u00e1\u0159e \/tmp\/snap-private-tmp\/$SNAP\/tmp\/.snap za \u00fa\u010delem nahrazen\u00ed obsahu sandboxov\u00e9ho prost\u0159ed\u00ed snap bal\u00ed\u010dku (metoda z\u00edsk\u00e1n\u00ed root je podobn\u00e1 prvn\u00ed zranitelnosti). \u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Qualys \u0432\u044b\u044f\u0432\u0438\u043b\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2026-3888) \u0432 \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u0440\u0430\u0431\u043e\u0442\u044b \u0441\u0432\u044f\u0437\u043a\u0438 snap-confine \u0438 systemd-tmpfiles \u0432 Ubuntu, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0443\u044e \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c root-\u0434\u043e\u0441\u0442\u0443\u043f \u043a \u0441\u0438\u0441\u0442\u0435\u043c\u0435. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0432 Ubuntu \u0432 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u0438 \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e \u043d\u0430\u0447\u0438\u043d\u0430\u044f \u0441 \u0432\u044b\u043f\u0443\u0441\u043a\u0430 24.04. \u0412 Ubuntu 16.04-22.04 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043c\u043e\u0436\u0435\u0442 \u0431\u044b\u0442\u044c \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0430 \u0432 \u043d\u0435\u0441\u0442\u0430\u043d\u0434\u0430\u0440\u0442\u043d\u044b\u0445 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u044f\u0445, \u0438\u043c\u0438\u0442\u0438\u0440\u0443\u044e\u0449\u0438\u0445 \u043f\u043e\u0432\u0435\u0434\u0435\u043d\u0438\u0435 \u0431\u043e\u043b\u0435\u0435 \u043d\u043e\u0432\u044b\u0445 \u0432\u0435\u0440\u0441\u0438\u0439 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430. \u0412 Ubuntu \u0438\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u0435 \u0434\u043e\u0441\u0442\u0443\u043f\u043d\u043e \u0432\u043e \u0432\u0447\u0435\u0440\u0430\u0448\u043d\u0435\u043c […]<\/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-165172","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Zranitelnosti ve snapd a Rust Coreutils, kter\u00e9 umo\u017e\u0148uj\u00ed z\u00edskat root privilegium v Ubuntu | ProHoster","description":"Spole\u010dnost Qualys odhalila zranitelnost (CVE-2026-3888) ve fungov\u00e1n\u00ed spojen\u00ed snap-confine a systemd-tmpfiles v Ubuntu, kter\u00e1 umo\u017e\u0148uje neprivilegovan\u00e9mu u\u017eivateli z\u00edskat root p\u0159\u00edstup k syst\u00e9mu.","canonical_url":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimosti-v-snapd-i-rust-soreutils-pozvolyayushhie-poluchit-root-privilegii-v-ubuntu","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"cs_CZ","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 snapd \u0438 Rust \u0421oreutils, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0438\u0435 \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c root-\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0438 \u0432 Ubuntu | ProHoster","og:description":"\u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Qualys \u0432\u044b\u044f\u0432\u0438\u043b\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2026-3888) \u0432 \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u0440\u0430\u0431\u043e\u0442\u044b \u0441\u0432\u044f\u0437\u043a\u0438 snap-confine \u0438 systemd-tmpfiles \u0432 Ubuntu, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0443\u044e \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c root-\u0434\u043e\u0441\u0442\u0443\u043f \u043a \u0441\u0438\u0441\u0442\u0435\u043c\u0435.","og:url":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimosti-v-snapd-i-rust-soreutils-pozvolyayushhie-poluchit-root-privilegii-v-ubuntu","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2026-03-18T15:12:13+00:00","article:modified_time":"2026-03-18T15:12:13+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":[],"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/165172","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/comments?post=165172"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/165172\/revisions"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media?parent=165172"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/categories?post=165172"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/tags?post=165172"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"