{"id":"CVE-2026-55159","state":"PUBLISHED","title":"luci-app-adblock-fast: Delegated `luci-app-adblock-fast` users can reach root command execution by injecting newline-separated cron entries","description":"luci-app-adblock-fast a WebUI for fast, lightweight DNS-based ad-blocker for OpenWrt that works with dnsmasq, smartdns, or unbound. Prior to 1.2.4-2, the luci.adblock-fast.setCronEntry RPC method accepts an entry argument containing carriage-return or line-feed characters and serializes it into /etc/crontabs/root as though it were one logical line. An authenticated delegated user with the luci-app-adblock-fast write ACL can therefore create an additional physical root cron entry through applications/luci-app-adblock-fast/root/usr/share/rpcd/ucode/luci.adblock-fast, resulting in persistent command execution as UID 0 when cron runs. The issue is not demonstrated for unauthenticated callers or users without the component write ACL. This vulnerability is fixed in 1.2.4-2.","publishedAt":"2026-09-21T19:24:03.581Z","updatedAt":"2026-09-29T14:01:11.023Z","severity":{"score":8.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["openwrt luci-app-adblock-fast"],"affected":[{"vendor":"openwrt","product":"luci-app-adblock-fast","versions":[{"version":"< 1.2.4-2","status":"affected"}]}],"references":["https://github.com/openwrt/luci/security/advisories/GHSA-ggpf-xrph-wg5v","https://github.com/openwrt/luci/pull/8705","https://github.com/openwrt/luci/commit/9ccd99b5898457e5ef39dc21aea226d7fb6e5c7e","https://github.com/openwrt/luci/commit/f67461fd0255bf992b2b559c22ec288067f2f9da"],"weaknesses":["CWE-93"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55159.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55159","state":"PUBLISHED","datePublished":"2026-09-21T19:24:03.581Z","dateUpdated":"2026-09-29T14:01:11.023Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T15:13:28.165Z"},"containers":{"cna":{"title":"luci-app-adblock-fast: Delegated `luci-app-adblock-fast` users can reach root command execution by injecting newline-separated cron entries","descriptions":[{"lang":"en","value":"luci-app-adblock-fast a WebUI for fast, lightweight DNS-based ad-blocker for OpenWrt that works with dnsmasq, smartdns, or unbound. Prior to 1.2.4-2, the luci.adblock-fast.setCronEntry RPC method accepts an entry argument containing carriage-return or line-feed characters and serializes it into /etc/crontabs/root as though it were one logical line. An authenticated delegated user with the luci-app-adblock-fast write ACL can therefore create an additional physical root cron entry through applications/luci-app-adblock-fast/root/usr/share/rpcd/ucode/luci.adblock-fast, resulting in persistent command execution as UID 0 when cron runs. The issue is not demonstrated for unauthenticated callers or users without the component write ACL. This vulnerability is fixed in 1.2.4-2."}],"affected":[{"vendor":"openwrt","product":"luci-app-adblock-fast","versions":[{"version":"< 1.2.4-2","status":"affected"}]}],"references":[{"url":"https://github.com/openwrt/luci/security/advisories/GHSA-ggpf-xrph-wg5v","name":"https://github.com/openwrt/luci/security/advisories/GHSA-ggpf-xrph-wg5v","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/openwrt/luci/pull/8705","name":"https://github.com/openwrt/luci/pull/8705","tags":["x_refsource_MISC"]},{"url":"https://github.com/openwrt/luci/commit/9ccd99b5898457e5ef39dc21aea226d7fb6e5c7e","name":"https://github.com/openwrt/luci/commit/9ccd99b5898457e5ef39dc21aea226d7fb6e5c7e","tags":["x_refsource_MISC"]},{"url":"https://github.com/openwrt/luci/commit/f67461fd0255bf992b2b559c22ec288067f2f9da","name":"https://github.com/openwrt/luci/commit/f67461fd0255bf992b2b559c22ec288067f2f9da","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":8.8,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-93","lang":"en","description":"CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-21T19:24:03.581Z"},"source":{"advisory":"GHSA-ggpf-xrph-wg5v","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/openwrt/luci/security/advisories/GHSA-ggpf-xrph-wg5v","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-29T14:01:03.903448Z","id":"CVE-2026-55159","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-29T14:01:11.023Z"}}]}}}