{"id":172666,"date":"2026-05-19T00:24:49","date_gmt":"2026-05-18T22:24:49","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/v-exim-4-99-3-ustranena-uyazvimost-pozvolyayushhaya-udalyonnoe-vypolnenie-koda-pri-ispolzovanii-gnutls"},"modified":"2026-05-19T00:24:49","modified_gmt":"2026-05-18T22:24:49","slug":"v-exim-4-99-3-ustranena-uyazvimost-pozvolyayushhaya-udalyonnoe-vypolnenie-koda-pri-ispolzovanii-gnutls","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/v-exim-4-99-3-ustranena-uyazvimost-pozvolyayushhaya-udalyonnoe-vypolnenie-koda-pri-ispolzovanii-gnutls","title":{"rendered":"Ve verzi Exim 4.99.3 byla odstran\u011bna zranitelnost, kter\u00e1 umo\u017e\u0148uje vzd\u00e1len\u00e9 spou\u0161t\u011bn\u00ed k\u00f3du p\u0159i pou\u017eit\u00ed GnuTLS.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V\u00fdvoj\u00e1\u0159i po\u0161tovn\u00edho serveru Exim vydali opravn\u00fdch release Exim 4.99.3<\/strong>, kter\u00fd odstra\u0148uje zranitelnost v n\u011bkter\u00fdch konfigurac\u00edch po\u0161tovn\u00edho agenta. Probl\u00e9m nese vnit\u0159n\u00ed identifik\u00e1tor EXIM-Security-2026-05-01.1<\/strong>; v ofici\u00e1ln\u00edm ozn\u00e1men\u00ed je tak\u00e9 uveden jako CVE-TBD<\/strong>.<\/p>\n

Zranitelnost spad\u00e1 do kategorie Remote Use-After-Free<\/strong> a projevuje se p\u0159i anal\u00fdze t\u011bla zpr\u00e1vy BDAT<\/strong> p\u0159i pou\u017eit\u00ed TLS p\u0159es GnuTLS<\/strong>. BDAT se pou\u017e\u00edv\u00e1 v roz\u0161\u00ed\u0159en\u00ed SMTP CHUNKING<\/strong> pro p\u0159enos t\u011bla zpr\u00e1vy po bloc\u00edch. Podle popisu Exim m\u016f\u017ee chyba nastat, kdy\u017e klient b\u011bhem p\u0159enosu BDAT ode\u0161le TLS ozn\u00e1men\u00ed close_notify p\u0159ed dokon\u010den\u00edm p\u0159enosu t\u011bla a n\u00e1sledn\u011b p\u0159id\u00e1 dal\u0161\u00ed byte v r\u00e1mci stejn\u00e9ho TCP spojen\u00ed.<\/p>\n

V takov\u00e9 posloupnosti m\u016f\u017ee Exim zapsat data do pam\u011b\u0165ov\u00e9ho bufferu, kter\u00fd byl ji\u017e uvoln\u011bn p\u0159i ukon\u010den\u00ed TLS relace. To vede k po\u0161kozen\u00ed haldy a potenci\u00e1ln\u011b m\u016f\u017ee b\u00fdt zneu\u017eito k vykon\u00e1n\u00ed k\u00f3du. V ozn\u00e1men\u00ed se zd\u016fraz\u0148uje, \u017ee \u00fato\u010dn\u00edk mus\u00ed m\u00edt schopnost nav\u00e1zat TLS spojen\u00ed a pou\u017e\u00edvat roz\u0161\u00ed\u0159en\u00ed SMTP CHUNKING \/ BDAT<\/strong>.<\/p>\n

Probl\u00e9m se t\u00fdk\u00e1 Exim 4.97, 4.98, 4.99, 4.99.1 a 4.99.2<\/strong>, ale pouze verze sestaven\u00e9 s podporou GnuTLS<\/strong>. V ofici\u00e1ln\u00ed dokumentaci je to formulov\u00e1no jako konfigurace s USE_GNUTLS=yes; verze, kter\u00e9 pou\u017e\u00edvaj\u00ed OpenSSL<\/strong> nebo jin\u00e9 TLS knihovny, touto zranitelnost\u00ed nejsou dot\u010deny. Tak\u00e9 v ozn\u00e1men\u00ed Exim je zvl\u00e1\u0161\u0165 uvedeno, \u017ee zraniteln\u00e9 jsou konfigurace, kde jsou vyhl\u00e1\u0161eny STARTTLS<\/strong> a CHUNKING<\/strong>.<\/p>\n

Oprava je zahrnuta v Exim 4.99.3<\/strong>. Podle popisu v\u00fdvoj\u00e1\u0159\u016f zaji\u0161\u0165uje patch \u010dist\u00e9 resetov\u00e1n\u00ed z\u00e1sobn\u00edku zpracov\u00e1n\u00ed vstupu p\u0159i obdr\u017een\u00ed TLS close_notify b\u011bhem aktivn\u00edho p\u0159enosu BDAT, co\u017e zabra\u0148uje dal\u0161\u00edmu vyu\u017eit\u00ed zastaral\u00fdch ukazatel\u016f. Jin\u00e9 zn\u00e1m\u00e9 zp\u016fsoby, jak zcela uzav\u0159\u00edt probl\u00e9m, krom\u011b aktualizace, nejsou v doporu\u010den\u00edch uvedeny.<\/p>\n

V\u00fdvoj\u00e1\u0159i Exim obdr\u017eeli hl\u00e1\u0161en\u00ed o chyb\u011b 1. kv\u011btna 2026<\/strong> od Federica Kirschbauma z XBOW Security<\/strong>. Po ov\u011b\u0159en\u00ed zpr\u00e1vy bylo opraven\u00ed p\u0159ipravov\u00e1no v uzav\u0159en\u00fdch repozit\u00e1\u0159\u00edch, 7. kv\u011btna byla o probl\u00e9mu informov\u00e1na distribuce prost\u0159ednictv\u00edm uzav\u0159en\u00e9ho mailing listu, 10. kv\u011btna jim byl poskytnut omezen\u00fd p\u0159\u00edstup k oprav\u00e1m, a 12. kv\u011btna 2026<\/strong> do\u0161lo k publikaci doporu\u010den\u00ed a samotn\u00e9ho vyd\u00e1n\u00ed s opravou.<\/p>\n

Spr\u00e1vc\u016fm po\u0161tovn\u00edch server\u016f se doporu\u010duje zkontrolovat pou\u017e\u00edvanou verzi Exim a TLS backend sestaven\u00ed. Pokud server<\/a> funguje na Eximu od verze 4.97 do 4.99.2 v\u010detn\u011b, sestaveno s GnuTLS a vyhla\u0161uje STARTTLS spolu s CHUNKING, projekt Exim doporu\u010duje co nejd\u0159\u00edve p\u0159ej\u00edt na Exim 4.99.3<\/strong> nebo nov\u011bj\u0161\u00ed verzi. Opraven\u00e9 zdrojov\u00e9 k\u00f3dy jsou k dispozici ve v\u011btvi exim-4.99+fixes a v ozna\u010den\u00ed exim-4.99.3, stejn\u011b jako ve form\u011b tarball archiv\u016f na b\u011b\u017en\u00fdch m\u00edstech pro stahov\u00e1n\u00ed Eximu.<\/p>\n

Zdroj: linux.org.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0420\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u0447\u0438\u043a\u0438 \u043f\u043e\u0447\u0442\u043e\u0432\u043e\u0433\u043e \u0441\u0435\u0440\u0432\u0435\u0440\u0430 Exim \u0432\u044b\u043f\u0443\u0441\u0442\u0438\u043b\u0438 \u043a\u043e\u0440\u0440\u0435\u043a\u0442\u0438\u0440\u0443\u044e\u0449\u0438\u0439 \u0440\u0435\u043b\u0438\u0437 Exim 4.99.3, \u0443\u0441\u0442\u0440\u0430\u043d\u044f\u044e\u0449\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u044f\u0445 \u043f\u043e\u0447\u0442\u043e\u0432\u043e\u0433\u043e \u0430\u0433\u0435\u043d\u0442\u0430. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u043e\u0445\u043e\u0434\u0438\u0442 \u043f\u043e\u0434 \u0432\u043d\u0443\u0442\u0440\u0435\u043d\u043d\u0438\u043c \u0438\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u043e\u043c EXIM-Security-2026-05-01.1; \u0432 \u043e\u0444\u0438\u0446\u0438\u0430\u043b\u044c\u043d\u043e\u043c \u0443\u0432\u0435\u0434\u043e\u043c\u043b\u0435\u043d\u0438\u0438 \u0442\u0430\u043a\u0436\u0435 \u0444\u0438\u0433\u0443\u0440\u0438\u0440\u0443\u0435\u0442 \u043a\u0430\u043a CVE-TBD. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043e\u0442\u043d\u043e\u0441\u0438\u0442\u0441\u044f \u043a \u043a\u043b\u0430\u0441\u0441\u0443 Remote Use-After-Free \u0438 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u043f\u0440\u0438 \u0440\u0430\u0437\u0431\u043e\u0440\u0435 \u0442\u0435\u043b\u0430 \u0441\u043e\u043e\u0431\u0449\u0435\u043d\u0438\u044f BDAT \u043f\u0440\u0438 \u0440\u0430\u0431\u043e\u0442\u0435 TLS \u0447\u0435\u0440\u0435\u0437 GnuTLS. BDAT \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u0442\u0441\u044f \u0432 SMTP-\u0440\u0430\u0441\u0448\u0438\u0440\u0435\u043d\u0438\u0438 CHUNKING \u0434\u043b\u044f \u043f\u0435\u0440\u0435\u0434\u0430\u0447\u0438 \u0442\u0435\u043b\u0430 […]<\/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-172666","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\udd47Ve verzi Exim 4.99.3 byla odstran\u011bna zranitelnost, kter\u00e1 umo\u017e\u0148ovala vzd\u00e1len\u00e9 spu\u0161t\u011bn\u00ed k\u00f3du p\u0159i pou\u017eit\u00ed GnuTLS | ProHoster","description":"V\u00fdvoj\u00e1\u0159i po\u0161tovn\u00edho serveru Exim vydali opravenou verzi Exim 4.99.3, kter\u00e1 odstra\u0148uje zranitelnost v n\u011bkter\u00fdch konfigurac\u00edch po\u0161tovn\u00edho agenta.","canonical_url":"https:\/\/prohoster.info\/cs\/blog\/news\/v-exim-4-99-3-ustranena-uyazvimost-pozvolyayushhaya-udalyonnoe-vypolnenie-koda-pri-ispolzovanii-gnutls","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\u0412 Exim 4.99.3 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e\u0435 \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u043a\u043e\u0434\u0430 \u043f\u0440\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 GnuTLS | ProHoster","og:description":"\u0420\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u0447\u0438\u043a\u0438 \u043f\u043e\u0447\u0442\u043e\u0432\u043e\u0433\u043e \u0441\u0435\u0440\u0432\u0435\u0440\u0430 Exim \u0432\u044b\u043f\u0443\u0441\u0442\u0438\u043b\u0438 \u043a\u043e\u0440\u0440\u0435\u043a\u0442\u0438\u0440\u0443\u044e\u0449\u0438\u0439 \u0440\u0435\u043b\u0438\u0437 Exim 4.99.3, \u0443\u0441\u0442\u0440\u0430\u043d\u044f\u044e\u0449\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u044f\u0445 \u043f\u043e\u0447\u0442\u043e\u0432\u043e\u0433\u043e \u0430\u0433\u0435\u043d\u0442\u0430.","og:url":"https:\/\/prohoster.info\/cs\/blog\/news\/v-exim-4-99-3-ustranena-uyazvimost-pozvolyayushhaya-udalyonnoe-vypolnenie-koda-pri-ispolzovanii-gnutls","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":"2026-05-18T22:24:49+00:00","article:modified_time":"2026-05-18T22:24:49+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\/172666","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=172666"}],"version-history":[{"count":1,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/172666\/revisions"}],"predecessor-version":[{"id":173168,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/172666\/revisions\/173168"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media?parent=172666"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/categories?post=172666"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/tags?post=172666"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}