How severe is CVE-2018-18320?

CVE-2018-18320 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-18320 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-18320?

CVE-2018-18320 primarily affects Asuswrt-merlin Project Rt-ac5300 Firmware. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-18320?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2018-18320 published?

CVE-2018-18320 was published on 2018-10-15 and last updated on 2026-06-17.

CVE-2018-18320

CVE-2018-18320 is a critical-severity vulnerability in Asuswrt-merlin Project Rt-ac5300 Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 5% (92nd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Asuswrt-merlin Project Rt-ac5300 Firmware
Published: 2018-10-15
Last modified: 2026-06-17

Description

An issue was discovered in the Merlin.PHP component 0.6.6 for Asuswrt-Merlin devices. An attacker can execute arbitrary commands because exec.php has a popen call. NOTE: the vendor indicates that Merlin.PHP is designed only for use on a trusted intranet network, and intentionally allows remote code execution

Frequently asked questions

What is CVE-2018-18320?: An issue was discovered in the Merlin.PHP component 0.6.6 for Asuswrt-Merlin devices. An attacker can execute arbitrary commands because exec.php has a popen call. NOTE: the vendor indicates that Merlin.PHP is designed only for use on a trusted intranet network, and intentionally allows remote code execution
How severe is CVE-2018-18320?: CVE-2018-18320 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-18320 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-18320?: CVE-2018-18320 primarily affects Asuswrt-merlin Project Rt-ac5300 Firmware. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-18320?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2018-18320 published?: CVE-2018-18320 was published on 2018-10-15 and last updated on 2026-06-17.

References

Affected products (14)

cpe:2.3:o:asuswrt-merlin_project:rt-ac5300_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt_ac1900p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac68u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac68p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac88u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac66u_b1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac56u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac3200_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac68uf_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac87_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac3100_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac1900_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac86u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asuswrt-merlin_project:rt-ac2900_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Asuswrt-merlin Project Rt-ac5300 Firmware

CVE-2018-18319 — Critical (CVSS 9.8): An issue was discovered in the Merlin.PHP component 0.6.6 for Asuswrt-Merlin devices. An attacker can execute arbitrary…
CVE-2017-11420 — Critical (CVSS 9.8): Stack-based buffer overflow in ASUS_Discovery.c in networkmap in Asuswrt-Merlin firmware for ASUS devices and ASUS…
CVE-2017-11345 — High (CVSS 7.8): Stack buffer overflow in networkmap in Asuswrt-Merlin firmware for ASUS devices and ASUS firmware for ASUS RT-AC5300,…
CVE-2017-11344 — High (CVSS 7.8): Global buffer overflow in networkmap in Asuswrt-Merlin firmware for ASUS devices and ASUS firmware for ASUS RT-AC5300,…

All CVEs affecting Asuswrt-merlin Project Rt-ac5300 Firmware →