A empresa Qualys identificou uma vulnerabilidade (CVE-2026-3888) na intera\u00e7\u00e3o entre snap-confine e systemd-tmpfiles no Ubuntu, permitindo que um usu\u00e1rio sem privil\u00e9gios obtenha acesso root ao sistema. O problema se manifesta no Ubuntu na configura\u00e7\u00e3o padr\u00e3o a partir da vers\u00e3o 24.04. No Ubuntu 16.04-22.04, a vulnerabilidade pode ser explorada em configura\u00e7\u00f5es n\u00e3o padr\u00e3o que imitam o comportamento de vers\u00f5es mais recentes da distribui\u00e7\u00e3o. No Ubuntu, a corre\u00e7\u00e3o est\u00e1 dispon\u00edvel na atualiza\u00e7\u00e3o de pacote snapd lan\u00e7ada ontem. No snapd, o problema foi resolvido na atualiza\u00e7\u00e3o 2.75. <\/p>\n
A vulnerabilidade surge devido \u00e0 intera\u00e7\u00e3o inadequada entre as utilidades snap-confine e systemd-tmpfiles, executadas com privil\u00e9gios elevados. A utilidade snap-confine configura um ambiente sandbox para a execu\u00e7\u00e3o de aplicativos snap, enquanto o systemd-tmpfiles realiza a limpeza autom\u00e1tica de arquivos e diret\u00f3rios tempor\u00e1rios. Por padr\u00e3o, a utilidade systemd-tmpfiles est\u00e1 configurada para remover todos os arquivos e diret\u00f3rios antigos em \/tmp, o que pode ser explorado por um invasor para substituir o diret\u00f3rio \/tmp\/.snap no momento ap\u00f3s sua remo\u00e7\u00e3o pela utilidade systemd-tmpfiles, mas antes de ser recriado pelo comando snap-confine. <\/p>\n
O ataque consiste em aguardar o in\u00edcio do processo de limpeza de arquivos tempor\u00e1rios, substituindo o diret\u00f3rio \/tmp\/.snap ap\u00f3s sua exclus\u00e3o e colocando uma c\u00f3pia modificada das bibliotecas em \/tmp\/.snap\/usr\/lib\/x86_64-linux-gnu.exchange. O atacante pode precisar esperar v\u00e1rios dias at\u00e9 que o systemd-tmpfiles seja acionado, pois no Ubuntu 24.04 o processo de limpeza \u00e9 executado a cada 10 dias, enquanto nas vers\u00f5es mais recentes \u2014 a cada 30 dias. Ap\u00f3s a substitui\u00e7\u00e3o do diret\u00f3rio, o atacante consegue inicializar um novo ambiente sandbox usando o snap-confine. <\/p>\n
Durante a forma\u00e7\u00e3o do ambiente sandbox no diret\u00f3rio tempor\u00e1rio \/tmp\/.snap, o invasor aguarda o momento certo e renomeia \/tmp\/.snap\/usr\/lib\/x86_64-linux-gnu.exchange para \/tmp\/.snap\/usr\/lib\/x86_64-linux-gnu, assim substituindo as bibliotecas e garantindo sua montagem bind com permiss\u00f5es de root. Assim, o invasor obt\u00e9m controle sobre as bibliotecas compartilhadas e o carregador ld.so, executados no ambiente sandbox do snap, e pode executar c\u00f3digo arbitr\u00e1rio com permiss\u00f5es de root ao iniciar qualquer programa suid que utilize liga\u00e7\u00e3o din\u00e2mica. <\/p>\n
Com acesso root no ambiente sandbox, isolado pelo AppArmor e um filtro de chamadas de sistema baseado em seccomp, o atacante pode copiar \/bin\/bash para o diret\u00f3rio \/var\/snap\/$SNAP\/common\/ e definir suas permiss\u00f5es como \u00ab04755\u00bb (suid root). Embora as permiss\u00f5es tenham sido alteradas dentro do ambiente sandbox, o arquivo com as permiss\u00f5es modificadas tamb\u00e9m est\u00e1 acess\u00edvel no sistema principal; portanto, para obter acesso root completo, basta executar \/var\/snap\/\/common\/bash com um usu\u00e1rio n\u00e3o privilegiado a partir do ambiente de sistema padr\u00e3o. <\/p>\n
Foi identificada uma vulnerabilidade na ferramenta uutils coreutils (Rust Coreutils), equivalente ao pacote GNU Coreutils, escrito em Rust. A vulnerabilidade permite que um usu\u00e1rio n\u00e3o privilegiado obtenha permiss\u00f5es de root no sistema. O problema foi detectado durante a revis\u00e3o de mudan\u00e7as no Ubuntu 25.10 e foi contornado antes do lan\u00e7amento do Ubuntu 25.10 atrav\u00e9s da entrega de \/usr\/bin\/gnurm em vez de uutils rm. No pacote uutils, o problema foi resolvido na vers\u00e3o 0.3.0 do uutils coreutils, sem men\u00e7\u00e3o na lista de mudan\u00e7as \u00e0 corre\u00e7\u00e3o da vulnerabilidade (foi indicado que rm, du, chmod e chgrp implementaram um m\u00e9todo seguro de contorno de caminhos). <\/p>\n
O problema \u00e9 causado por uma condi\u00e7\u00e3o de corrida na ferramenta \u00abrm\u00bb, permitindo que um usu\u00e1rio local substitua o conte\u00fado de um diret\u00f3rio por um link simb\u00f3lico durante a exclus\u00e3o de um arquivo controlado pelo usu\u00e1rio pelo processo \u00abrm\u00bb com privil\u00e9gios de root. Entre outras coisas, a vulnerabilidade pode ser explorada durante a execu\u00e7\u00e3o di\u00e1ria do script do cron \/etc\/cron.daily\/apport, que \u00e9 executado com privil\u00e9gios de root e exclui recursivamente o conte\u00fado do diret\u00f3rio \/var\/crash, acess\u00edvel para escrita por todos os usu\u00e1rios do sistema. <\/p>\n
Durante a remo\u00e7\u00e3o recursiva de diret\u00f3rios, a ferramenta rm primeiro verifica todos os diret\u00f3rios e depois os remove de forma sequencial na ordem inversa, chamando a fun\u00e7\u00e3o rmdir(). Se for realizada a substitui\u00e7\u00e3o do diret\u00f3rio pai por um link simb\u00f3lico imediatamente ap\u00f3s a verifica\u00e7\u00e3o desse diret\u00f3rio, mas antes da verifica\u00e7\u00e3o dos diret\u00f3rios filhos contidos nele, a opera\u00e7\u00e3o resultar\u00e1 na remo\u00e7\u00e3o do diret\u00f3rio para o qual o link simb\u00f3lico aponta. Dessa forma, \u00e9 poss\u00edvel n\u00e3o apenas remover qualquer arquivo no sistema, mas tamb\u00e9m elevar privil\u00e9gios atrav\u00e9s da remo\u00e7\u00e3o do diret\u00f3rio \/tmp\/snap-private-tmp\/$SNAP\/tmp\/.snap para substituir o conte\u00fado do ambiente sandbox do pacote snap (o m\u00e9todo de obten\u00e7\u00e3o de root \u00e9 semelhante \u00e0 primeira vulnerabilidade). \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\udd47 Vulnerabilidades no snapd e Coreutils Rust, que permitem obter privil\u00e9gios de root no Ubuntu | ProHoster","description":"A empresa Qualys identificou uma vulnerabilidade (CVE-2026-3888) na organiza\u00e7\u00e3o do trabalho entre snap-confine e systemd-tmpfiles no Ubuntu, permitindo que um usu\u00e1rio n\u00e3o privilegiado obtenha acesso root ao 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Fonte: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"