How severe is CVE-2018-8879?

CVE-2018-8879 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-2018-8879 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-8879?

CVE-2018-8879 affects Asus Rt-ac66u Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-8879?

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-2018-8879 published?

CVE-2018-8879 was published on 2019-11-21 and last updated on 2026-06-17.

CVE-2018-8879

CVE-2018-8879 is a critical-severity vulnerability in Asus Rt-ac66u Firmware with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 17% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 17% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Asus Rt-ac66u Firmware
Published: 2019-11-21
Last modified: 2026-06-17

Description

Stack-based buffer overflow in Asuswrt-Merlin firmware for ASUS devices older than 384.4 and ASUS firmware before 3.0.0.4.382.50470 for devices allows remote attackers to execute arbitrary code by providing a long string to the blocking.asp page via a GET or POST request. Vulnerable parameters are flag, mac, and cat_id.

Frequently asked questions

What is CVE-2018-8879?: Stack-based buffer overflow in Asuswrt-Merlin firmware for ASUS devices older than 384.4 and ASUS firmware before 3.0.0.4.382.50470 for devices allows remote attackers to execute arbitrary code by providing a long string to the blocking.asp page via a GET or POST request. Vulnerable parameters are flag, mac, and cat_id.
How severe is CVE-2018-8879?: CVE-2018-8879 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-2018-8879 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-8879?: CVE-2018-8879 affects Asus Rt-ac66u Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-8879?: 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-2018-8879 published?: CVE-2018-8879 was published on 2019-11-21 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:asus:rt-ac66u_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Asus Rt-ac66u Firmware

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CVE-2018-9285 — Critical (CVSS 9.8): Main_Analysis_Content.asp in /apply.cgi on ASUS RT-AC66U, RT-AC68U, RT-AC86U, RT-AC88U, RT-AC1900, RT-AC2900, and…
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