CVE-2026-72840: Incorrect Privilege Assignment in openwrt luci
CVE-2026-72840 is a high-severity vulnerability in OpenWrt LuCI where an overly permissive ACL in luci-mod-system-mounts allows authenticated users with mount-configuration privileges to write to /etc/crontabs/root. This enables them to append arbitrary cron jobs executed by the root-owned busybox crond daemon within one minute.
AI Analysis
Technical Summary
OpenWrt LuCI contains an incorrect privilege assignment vulnerability due to an overly permissive ACL definition in the luci-mod-system-mounts module. Authenticated users assigned only to the mount-configuration ACL group can exploit this flaw to gain write access to the root user's crontab file (/etc/crontabs/root) via the ubus file.write interface. Because the default busybox crond daemon runs these cron jobs as root, this allows privilege escalation by executing arbitrary commands with root privileges.
Potential Impact
An authenticated user with limited mount-configuration permissions can escalate privileges to root by appending arbitrary cron jobs. This could lead to full system compromise, unauthorized command execution, and persistent control over the affected device.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the mount-configuration ACL group to trusted users only and monitor for suspicious cron file modifications.
CVE-2026-72840: Incorrect Privilege Assignment in openwrt luci
Description
CVE-2026-72840 is a high-severity vulnerability in OpenWrt LuCI where an overly permissive ACL in luci-mod-system-mounts allows authenticated users with mount-configuration privileges to write to /etc/crontabs/root. This enables them to append arbitrary cron jobs executed by the root-owned busybox crond daemon within one minute.
CVSS v4.0
Score 8.7high
Affected software
openwrt
luci
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
OpenWrt LuCI contains an incorrect privilege assignment vulnerability due to an overly permissive ACL definition in the luci-mod-system-mounts module. Authenticated users assigned only to the mount-configuration ACL group can exploit this flaw to gain write access to the root user's crontab file (/etc/crontabs/root) via the ubus file.write interface. Because the default busybox crond daemon runs these cron jobs as root, this allows privilege escalation by executing arbitrary commands with root privileges.
Potential Impact
An authenticated user with limited mount-configuration permissions can escalate privileges to root by appending arbitrary cron jobs. This could lead to full system compromise, unauthorized command execution, and persistent control over the affected device.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the mount-configuration ACL group to trusted users only and monitor for suspicious cron file modifications.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-10T15:13:41.486Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a7e412ebf8831d539e05145
Added to database: 08/13/2026, 22:11:58 UTC
Last enriched: 08/21/2026, 13:27:49 UTC
Last updated: 09/26/2026, 13:47:48 UTC
Views: 59
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