Stack-based buffer overflow in the ej_update_variables function in router/httpd/web.c on…
Priority MEDIUM 42CWE-787Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-787 and the CVSS impact.
Summary
Stack-based buffer overflow in the ej_update_variables function in router/httpd/web.c on ASUS routers (when using software from https://github.com/RMerl/asuswrt-merlin) allows web authenticated attackers to execute code via a request that updates a setting. In ej_update_variables, the length of the variable action_script is not checked, as long as it includes a "_wan_if" substring.
Why it matters now
EPSS 0.01938 80th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:asuswrt-merlin:asuswrt-merlin:*:*:*:*:*:*:*:* | up to 382.1_2 | Vulnerable | Asuswrt-Merlin |
- cpe:2.3:o:asuswrt-merlin:asuswrt-merlin:*:*:*:*:*:*:*:* Versions up to 382.1_2 Vulnerable ·Asuswrt-Merlin
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2018-5721
- 2026-10-03 Alias added: GHSA-8hc5-mr39-qw3v
More Asuswrt-merlin vulnerabilities
- TI-2017-09447 Stack buffer overflow in httpd in Asuswrt-Merlin firmware 380.67_0RT-AC5300 and earlier… CVSS 3.1HIGH 8.8
- TI-2018-06420 Information disclosure in Asuswrt-Merlin firmware for ASUS devices older than 384.4 and… CVSS 3.1MEDIUM 5.3
- TI-2018-06419 Information disclosure in Asuswrt-Merlin firmware for ASUS devices older than 384.4 and… CVSS 3.1MEDIUM 5.3
Sources
- CVE-2018-5721 · CVE Program
- CVE-2018-5721 · NVD
- FIRST EPSS
- GHSA-8hc5-mr39-qw3v · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences