How severe is CVE-2021-25810?

CVE-2021-25810 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-25810 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-25810?

CVE-2021-25810 affects Mercusys Mercury X18g Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-25810?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-25810 published?

CVE-2021-25810 was published on 2021-04-29 and last updated on 2026-06-17.

CVE-2021-25810

CVE-2021-25810 is a medium-severity vulnerability in Mercusys Mercury X18g Firmware with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Mercusys Mercury X18g Firmware
Published: 2021-04-29
Last modified: 2026-06-17

Description

Cross site Scripting (XSS) vulnerability in MERCUSYS Mercury X18G 1.0.5 devices, via crafted values to the 'src_dport_start', 'src_dport_end', and 'dest_port' parameters.

Frequently asked questions

What is CVE-2021-25810?: Cross site Scripting (XSS) vulnerability in MERCUSYS Mercury X18G 1.0.5 devices, via crafted values to the 'src_dport_start', 'src_dport_end', and 'dest_port' parameters.
How severe is CVE-2021-25810?: CVE-2021-25810 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-25810 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-25810?: CVE-2021-25810 affects Mercusys Mercury X18g Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-25810?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-25810 published?: CVE-2021-25810 was published on 2021-04-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:mercusys:mercury_x18g_firmware:1.0.5:*:*:*:*:*:*:*

More vulnerabilities in Mercusys Mercury X18g Firmware

CVE-2021-25811 — High (CVSS 7.5): MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST listen_http_lan parameter.…
CVE-2021-23242 — Medium (CVSS 5.3): MERCUSYS Mercury X18G 1.0.5 devices allow Directory Traversal via ../ to the UPnP server, as demonstrated by the…
CVE-2021-23241 — Medium (CVSS 5.3): MERCUSYS Mercury X18G 1.0.5 devices allow Directory Traversal via ../ in conjunction with a loginLess or login.htm URI…

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