Is CVE-2026-26991 in the CISA KEV catalog?

No. CVE-2026-26991 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-26991?

CVE-2026-26991 has a CVSS v3 base score of 4.8 (MEDIUM).

What is the EPSS score for CVE-2026-26991?

CVE-2026-26991 has an EPSS score of 0.22% (12th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-26991?

Upgrade librenms to 26.2.0 or later.

CVE & CISA-KEV Catalog

CVE-2026-26991

MEDIUM

4.8

CVSS v3

NVD

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

librenmsNVD

Affected:< 26.2.0Fixed in:26.2.0CVE-2026-26991derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredHigh

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

0.22%probability of exploitation in 30 days

12thpercentile

Low risk: more likely to be exploited than 12% of all known CVEs.

References

Patch1

github.com

Exploit1

github.com

Issue Tracking1

github.com

Release Notes1

github.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-02-20.