CVE-2026-55159 Command injection in luci-app-adblock-fast
Authenticated users with write access can inject newlines into cron entries to execute arbitrary commands as root on OpenWrt devices.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55159?
CVE-2026-55159 is a high-severity command injection vulnerability in openwrt luci-app-adblock-fast, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
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.
Weakness: CWE-93
Which versions are affected by CVE-2026-55159?
How do I fix CVE-2026-55159?
No fix has been published for CVE-2026-55159 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-55159 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55159 exists.
Sources
Also known as GHSA-ggpf-xrph-wg5v.