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TI-2026-39848 Aliases CVE-2026-55159

luci-app-adblock-fast: Delegated `luci-app-adblock-fast` users can reach root command…

Priority HIGH 73CWE-93Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00662 51st percentileScored 2026-11-07
Fix Fixed luci-app-adblock-fast (openwrt): 1.2.4-2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
openwrtluci-app-adblock-fastbefore 1.2.4-21.2.4-2Patch availableCNA
  • luci-app-adblock-fast Vendoropenwrt Affected before 1.2.4-2 Fixed in 1.2.4-2 Patch available CNA

Remediation

  • Fix · CNA luci-app-adblock-fast (openwrt) Fixed in 1.2.4-2

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55159
  2. 2026-10-25 EPSS moved to the 50th–90th percentile

References

Other 4

  • TI-2026-79903 Stack buffer overflow in odhcpd DHCPv6 IA reply handling CVSS 3.1CRITICAL 9.8
  • TI-2024-13053 Improper input validation in MediaTek MT6890, MT7915, MT7916, MT7981, MT7986 CVSS 3.1CRITICAL 9.8
  • TI-2026-79901 Use-after-free in odhcpd DHCPv6 IA handling CVSS 4.0HIGH 8.8
  • TI-2026-48502 OpenWrt luci-app-bmx7 Path Traversal via bmx7-info CVSS 4.0HIGH 8.7
  • TI-2026-44407 luci-app-banip Log Monitor IP Extraction Bypass CVSS 4.0HIGH 8.7
  • TI-2026-51067 luci-app-openvpn Path Traversal RCE via instance_name2 CVSS 4.0CRITICAL 9.4
See all 168 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences