How severe is CVE-2026-26991?

CVE-2026-26991 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-26991 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26991?

CVE-2026-26991 affects Librenms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-26991?

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

Does CVE-2026-26991 have an EU (EUVD) identifier?

Yes. CVE-2026-26991 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8340.

When was CVE-2026-26991 published?

CVE-2026-26991 was published on 2026-02-20 and last updated on 2026-06-17.

CVE-2026-26991

CVE-2026-26991 is a medium-severity vulnerability in Librenms with a CVSS 3.x base score of 4.8. 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 4.8)
CVSS v4: 5.1
EPSS exploit prediction: 0% (12th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8340
Weakness: CWE-79
Affected product: Librenms
Published: 2026-02-20
Last modified: 2026-06-17

Description

LibreNMS is an auto-discovering PHP/MySQL/SNMP based network monitoring tool. In versions 26.1.1 and below, the device group name is not sanitized, allowing attackers with admin privileges to perform Stored Cross-Site Scripting (XSS) attacks. When a user adds a device group, an HTTP POST request is sent to the Request-URI "/device-groups". The name of the newly created device group is stored in the value of the name parameter. After the device group is created, the entry is displayed along with relevant buttons such as Rediscover Devices, Edit, and Delete. This issue has been fixed in version 26.2.0.

Frequently asked questions

What is CVE-2026-26991?: LibreNMS is an auto-discovering PHP/MySQL/SNMP based network monitoring tool. In versions 26.1.1 and below, the device group name is not sanitized, allowing attackers with admin privileges to perform Stored Cross-Site Scripting (XSS) attacks. When a user adds a device group, an HTTP POST request is sent to the Request-URI "/device-groups". The name of the newly created device group is stored in the value of the name parameter. After the device group is created, the entry is displayed along with relevant buttons such as Rediscover Devices, Edit, and Delete. This issue has been fixed in version 26.2.0.
How severe is CVE-2026-26991?: CVE-2026-26991 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-26991 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26991?: CVE-2026-26991 affects Librenms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-26991?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-26991 have an EU (EUVD) identifier?: Yes. CVE-2026-26991 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8340.
When was CVE-2026-26991 published?: CVE-2026-26991 was published on 2026-02-20 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:librenms:librenms:*:*:*:*:*:*:*:*

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