{"id":182826,"date":"2026-08-11T04:54:22","date_gmt":"2026-08-11T02:54:22","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/v-freenginx-i-nginx-dobavili-proverku-razmera-tekstovoj-peremennoj-pered-tem-kak-zapisyvat-v-neyo-dannye-cve"},"modified":"2026-08-11T04:54:22","modified_gmt":"2026-08-11T02:54:22","slug":"v-freenginx-i-nginx-dobavili-proverku-razmera-tekstovoj-peremennoj-pered-tem-kak-zapisyvat-v-neyo-dannye-cve","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/v-freenginx-i-nginx-dobavili-proverku-razmera-tekstovoj-peremennoj-pered-tem-kak-zapisyvat-v-neyo-dannye-cve","title":{"rendered":"Do freenginx a nginx byla p\u0159id\u00e1na kontrola velikosti textov\u00e9 prom\u011bnn\u00e9 p\u0159ed t\u00edm, ne\u017e se do n\u00ed zap\u00ed\u0161\u00ed data (+ CVE)","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

<\/i><\/a>
3 <\/p>\n

TL;DR<\/b>: Kdy\u017e se v roce 2026 objevilo t\u0159et\u00ed zji\u0161t\u011bn\u00e9 p\u0159ete\u010den\u00ed pam\u011bti (a podle F5, RCE bez ASLR) p\u0159i pr\u00e1ci s regul\u00e1rn\u00edmi v\u00fdrazy a prom\u011bnn\u00fdmi, v\u00fdvoj\u00e1\u0159 freenginxu Maxim Dunin usoudil, \u017ee je na \u010dase to ukon\u010dit, a p\u0159idal do sv\u00e9ho produktu kontrolu velikosti prom\u011bnn\u00e9 p\u0159ed t\u00edm, ne\u017e do n\u00ed zap\u00ed\u0161e data. Odtud toto novum p\u0159evzali k sob\u011b i nginx, co\u017e d\u00e1v\u00e1 nad\u011bji na ukon\u010den\u00ed nov\u00fdch CVE na toto t\u00e9ma.<\/p>\n

Te\u010f podrobnosti.<\/p>\n

Dne 19. \u010dervna byla provedena commit<\/a> \u00faprava ve freenginxu, kter\u00e1 p\u0159id\u00e1v\u00e1 do popisova\u010de prom\u011bnn\u00e9 pole end, ur\u010duj\u00edc\u00ed konec bufferu. D\u0159\u00edve tam byl pouze ukazatel na jeho za\u010d\u00e1tek (pos), pot\u0159ebn\u00e1 d\u00e9lka byla vypo\u010d\u00edt\u00e1v\u00e1na (a st\u00e1le se vypo\u010d\u00edt\u00e1v\u00e1) p\u0159edem, a v okam\u017eiku zkop\u00edrov\u00e1n\u00ed do prom\u011bnn\u00e9 se p\u0159edpokl\u00e1dalo, \u017ee spr\u00e1vn\u011b d\u0159\u00edve vypo\u010d\u00edtan\u00e1 d\u00e9lka zaru\u010duje, \u017ee data se vejdou do bufferu. Bohu\u017eel ji\u017e dvakr\u00e1t v kv\u011btnu 2026 kv\u016fli r\u016fzn\u00fdm p\u0159ehl\u00e9dnut\u00edm to tak nebylo (1 (linux.org.ru)<\/a>, 2 (linux.org.ru)<\/a>), co\u017e vedlo k p\u0159ete\u010den\u00ed bufferu a \u0161patn\u00fdm n\u00e1sledk\u016fm. Tak tedy, nyn\u00ed p\u0159i vytv\u00e1\u0159en\u00ed bufferu prom\u011bnn\u00e9 se vypl\u0148uje i ukazatel na jej\u00ed konec, a p\u0159ed z\u00e1pisem do prom\u011bnn\u00e9 dat, pokud se do n\u00ed data nevejdou, zpracov\u00e1n\u00ed po\u017eadavku bude kontrolovan\u011b ukon\u010deno s chybou. To znamen\u00e1, \u017ee chyby ve v\u00fdpo\u010dtu d\u00e9lky mohou i nad\u00e1le existovat, ale nyn\u00ed nebudou naru\u0161ovat pam\u011b\u0165, ale pouze sel\u017eou konkr\u00e9tn\u00ed http-po\u017eadavek. N\u00e1sleduj\u00edc\u00edmi commity (2 (freenginx.org)<\/a>, 3 (freenginx.org)<\/a>) byla p\u0159id\u00e1na podobn\u00e1 ochrana na jin\u00e1 m\u00edsta v k\u00f3du, v\u010detn\u011b k\u00f3du pro veden\u00ed access-logu. Dne 7. \u010dervence byla zve\u0159ejn\u011bna verze freenginx 1.31.3<\/a>, kter\u00e1 obsahuje tuto opravu.<\/p>\n

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Dne 15. \u010dervence byly tyto commity p\u0159evzaty nginxem (1 (github.com)<\/a>, 2 (github.com)<\/a>, 3 (github.com)<\/a>, ov\u0161em z n\u011bjak\u00e9ho d\u016fvodu byla prohozen\u00e1 druh\u00e1 a t\u0159et\u00ed v \u0159et\u011bzci), probl\u00e9mu byl p\u0159id\u011blen CVE-2026-42533<\/a>, a F5 vydalo ofici\u00e1ln\u00ed SA (f5.com)<\/a>.<\/p>\n

<\/noindex><\/p>\n

Pokud jde o konkr\u00e9tn\u00ed zranitelnost tentokr\u00e1t: ta se projevuje p\u0159i pou\u017eit\u00ed direktivy map s regul\u00e1rn\u00edmi v\u00fdrazy se zv\u00fdrazn\u011bn\u00fdmi parametry. Ohledn\u011b ostatn\u00edch podm\u00ednek pot\u0159ebn\u00fdch k jej\u00edmu vyvol\u00e1n\u00ed se text v popisu commitu a text v SA m\u00edrn\u011b li\u0161\u00ed: v SA je uvedeno, \u017ee by m\u011blo doj\u00edt k v\u00fdpo\u010dtu n\u011bjak\u00e9ho \u0159et\u011bzce, kter\u00fd vyu\u017e\u00edv\u00e1 zv\u00fdrazn\u011bn\u00fd parametr z map, d\u0159\u00edve ne\u017e v\u00fdsledek tohoto map. V popisu commitu je v p\u0159\u00edkladu mezi t\u011bmito kroky tak\u00e9 zahrnuto nulov\u00e1n\u00ed prom\u011bnn\u00e9, kter\u00e1 obsahuje zv\u00fdrazn\u011bn\u00fd parametr. Tak \u010di onak, v\u011bt\u0161ina b\u011b\u017e\u00edc\u00edch nginx\u016f s t\u00edmto pravd\u011bpodobn\u011b nebude m\u00edt zku\u0161enosti, a zranitelnost tak zas\u00e1hla jen m\u00e1lo lid\u00ed. Tak\u00e9 stoj\u00ed za zm\u00ednku, \u017ee opravy v\u00fdpo\u010dtu d\u00e9lky v tomto konkr\u00e9tn\u00edm p\u0159\u00edpad\u011b ve commitovan\u00fdch zm\u011bn\u00e1ch zd\u00e1 se nejsou (nebo jsem \u0161patn\u011b hledal?), existuje pouze ochrana, kter\u00e1 probl\u00e9m \u043f\u0440\u0435\u0432\u0440\u0430\u0449\u0430\u0435\u0442 \u043d\u0430 \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u0438\u0440\u0443\u0435\u043c\u00fd \u0444\u0435\u0439\u043b http-\u0437\u0430\u043f\u0440\u043e\u0441\u0430. Nicm\u00e9n\u011b 19. \u010dervence byly do freenginx p\u0159id\u00e1ny n\u011bjak\u00e9 opravy (5bfb<\/a>, 7622<\/a>, b906<\/a>) v\u00fdpo\u010dtu d\u00e9lky pro podobnou situaci, ale p\u0159esn\u011b to z fleku nepochop\u00edm, jestli to je ono nebo ne. <\/p>\n

Zranitelnost se objevila ve verzi nginx 0.9.6, opravy se dostaly do verz\u00ed freenginx 1.31.3, nginx 1.30.4, nginx 1.31.3.<\/p>\n

V SA nginx jsou vyj\u00e1d\u0159eny d\u00edky n\u011bkolika osob\u00e1m za nez\u00e1visl\u00e9 zpr\u00e1vy o zranitelnosti a za dodr\u017eov\u00e1n\u00ed \u201estandard\u016f koordinovan\u00e9ho zve\u0159ej\u0148ov\u00e1n\u00ed informac\u00ed\u201c:<\/p>\n

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F5 uzn\u00e1v\u00e1 Minga Xuana, DKD (@pidifn), Ji\u2019ana Zhoua a Zhen Yana z AntAISecurityLab, Rafaela Gacka, Serhiiho Negodiuka z EVO.company, Lama Jun Ronga z Calif.io, Mufeed VH z Winfunc Research (winfunc.com), Vexera AI (https:\/\/vexera.ai<\/a>), Tu Trana Dinha (@1w4y), Stana Shawa (cyberstan), qianshuidewajueji, zennetha (randomguy6407), Zhenpenga (Leo) Lina z depthfirst, Lukase Johannese Moellera, Melih Tolga Sahina z Vodafone T\u00fcrkiye, Ayouba Nabila Boubagrata (GitHub: @ayoubnabil) a Milana Jovice (Kljunowsky) za to, \u017ee n\u00e1s na tento probl\u00e9m nez\u00e1visle upozornili a dodr\u017eovali nejvy\u0161\u0161\u00ed standardy koordinovan\u00e9ho zve\u0159ejn\u011bn\u00ed.<\/p>\n

<\/noindex><\/p><\/blockquote>\n

Ve freenginx je doprovodn\u00e9 informace o oprav\u011b v podstat\u011b omezena na zpr\u00e1vu p\u0159i commitu. V changelog<\/a>- tohle opraven\u00ed nen\u00ed ozna\u010deno ani podpisem \u201ebezpe\u010dnost\u201c (security), ani \u201eopraven\u00ed\u201c (bugfix), ale pouze \u201ep\u0159id\u00e1n\u00ed\u201c (feature). Pravd\u011bpodobn\u011b autor tuto z\u00e1le\u017eitost nepova\u017eoval za kritickou. Jak se zpr\u00e1vy o probl\u00e9mu od uveden\u00fdch osob ve F5 vztahuj\u00ed k z\u00edskan\u00e9mu commitu z freenginx, zda oni (nebo n\u011bkdo jin\u00fd) informovali autora freenginx o probl\u00e9mu, se zjistit nepoda\u0159ilo. <\/p>\n

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

3 TL;DR: \u0421\u0442\u043e\u043b\u043a\u043d\u0443\u0432\u0448\u0438\u0441\u044c \u0441 \u0442\u0440\u0435\u0442\u044c\u0438\u043c \u043e\u0431\u043d\u0430\u0440\u0443\u0436\u0435\u043d\u043d\u044b\u043c \u0437\u0430 2026 \u0433\u043e\u0434 \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435\u043c \u0431\u0443\u0444\u0435\u0440\u0430 (\u0438, \u043f\u043e \u0432\u0435\u0440\u0441\u0438\u0438 F5, RCE \u0435\u0441\u043b\u0438 \u043d\u0435\u0442 ASLR) \u043f\u0440\u0438 \u0440\u0430\u0431\u043e\u0442\u0435 \u0441 \u0440\u0435\u0433\u044d\u043a\u0441\u043f\u0430\u043c\u0438 \u0438 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u044b\u043c\u0438, \u0440\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u0447\u0438\u043a freenginx \u041c\u0430\u043a\u0441\u0438\u043c \u0414\u0443\u043d\u0438\u043d \u0440\u0435\u0448\u0438\u043b, \u0447\u0442\u043e \u043f\u043e\u0440\u0430 \u044d\u0442\u043e \u043f\u0440\u0435\u043a\u0440\u0430\u0449\u0430\u0442\u044c, \u0438 \u0434\u043e\u0431\u0430\u0432\u0438\u043b \u0432 \u0441\u0432\u043e\u0439 \u043f\u0440\u043e\u0434\u0443\u043a\u0442 \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0443 \u0440\u0430\u0437\u043c\u0435\u0440\u0430 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u043e\u0439 \u043f\u0435\u0440\u0435\u0434 \u0442\u0435\u043c \u043a\u0430\u043a \u0437\u0430\u043f\u0438\u0441\u044b\u0432\u0430\u0442\u044c \u0432 \u043d\u0435\u0451 \u0434\u0430\u043d\u043d\u044b\u0435. \u041e\u0442\u0442\u0443\u0434\u0430 \u044d\u0442\u043e \u043d\u043e\u0432\u043e\u0432\u0432\u0435\u0434\u0435\u043d\u0438\u0435 \u0443\u0442\u0430\u0449\u0438\u043b\u0438 \u043a \u0441\u0435\u0431\u0435 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":9,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-182826","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\n","aioseo_head_json":{"title":"\ud83e\udd47Do freenginx a nginx byla p\u0159id\u00e1na kontrola velikosti textov\u00e9 prom\u011bnn\u00e9 p\u0159ed jej\u00edm z\u00e1pisem dat (+ CVE) | ProHoster","description":"3 TL;DR: Vzhledem k t\u0159et\u00edmu zji\u0161t\u011bn\u00e9mu p\u0159ete\u010den\u00ed bufferu za rok 2026 (a podle 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\u0442\u0435\u043c \u043a\u0430\u043a \u0437\u0430\u043f\u0438\u0441\u044b\u0432\u0430\u0442\u044c \u0432 \u043d\u0435\u0451 \u0434\u0430\u043d\u043d\u044b\u0435 (+ CVE) | ProHoster","og:description":"3 TL;DR: \u0421\u0442\u043e\u043b\u043a\u043d\u0443\u0432\u0448\u0438\u0441\u044c \u0441 \u0442\u0440\u0435\u0442\u044c\u0438\u043c \u043e\u0431\u043d\u0430\u0440\u0443\u0436\u0435\u043d\u043d\u044b\u043c \u0437\u0430 2026 \u0433\u043e\u0434 \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435\u043c \u0431\u0443\u0444\u0435\u0440\u0430 (\u0438, \u043f\u043e \u0432\u0435\u0440\u0441\u0438\u0438 F5.","og:url":"https:\/\/prohoster.info\/cs\/blog\/news\/v-freenginx-i-nginx-dobavili-proverku-razmera-tekstovoj-peremennoj-pered-tem-kak-zapisyvat-v-neyo-dannye-cve","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":"2026-08-11T02:54:22+00:00","article:modified_time":"2026-08-11T02:54:22+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":{"post_id":"182826","title":null,"description":null,"keywords":null,"keyphrases":{"focus":[],"additional":[]},"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":"default","schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"seo_analyzer_scan_date":null,"breadcrumb_settings":null,"limit_modified_date":false,"reviewed_by":null,"ai":null,"created":"2026-08-11 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