Vulnerability · Published Sep 21, 2026 · Assigned by GitHub_M
CVE-2026-55159luci-app-adblock-fast: Delegated `luci-app-adblock-fast` users can reach root command execution by injecting newline-separated cron entries
High 8.8
In plain English
A high-severity security flaw in luci-app-adblock-fast from openwrt. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| openwrt | luci-app-adblock-fast | < 1.2.4-2 |
Weakness: CWE-93 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://github.com/openwrt/luci/security/advisories/GHSA-ggpf-xrph-wg5v x_refsource_CONFIRM
- https://github.com/openwrt/luci/pull/8705 x_refsource_MISC
- https://github.com/openwrt/luci/commit/9ccd99b5898457e5ef39dc21aea226d7fb6e5c7e x_refsource_MISC
- https://github.com/openwrt/luci/commit/f67461fd0255bf992b2b559c22ec288067f2f9da x_refsource_MISC