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CVE-2026-84193· NVD / CVE Program· CNA VulnCheck

LibreNMS through 26.2.0 Stored Cross-Site Scripting via SNMP

LibreNMS through 26.2.0 contains a stored cross-site scripting vulnerability in legacy PHP template pages that render unescaped SNMP-sourced data fields including BGP peer descriptions, VRF names, process information, and SLA tags. Attackers with device management access or network access to enroll a rogue SNMP device can inject malicious JavaScript that executes when admins view affected routing and device pages, enabling credential theft and CSRF token exfiltration.

MediumCVSS 5.8 · v4.0—No exploit No fix recorded
Published
Sep 1, 2026
Updated
Sep 8, 2026
EPSS
0.3% · 27th percentile
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Action score

23

Monitor

Low priority for now.

CVSS
23 / 40 · 5.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
5.8
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • librenms librenms

    • up to and including 26.2.0affected · semver

Same product

librenms: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-20434LibreNMS 1.46 allows remote attackers to execute arbitrary OS commands by using the $_POST['community'] parameter to html/pages/addhost.inc.
    60This week
  • CVE-2019-10669An issue was discovered in LibreNMS through 1.47.
    52Plan
  • CVE-2022-4067Cross-site Scripting (XSS) - Stored in librenms/librenms
    49Plan
  • CVE-2022-3562Cross-site Scripting (XSS) - Stored in librenms/librenms
    49Plan
  • CVE-2022-4069Cross-site Scripting (XSS) - Generic in librenms/librenms
    47Plan
  • CVE-2024-49754LibreNMS has a stored XSS ('Cross-site Scripting') in librenms/includes/html/pages/api-access.inc.php
    43Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-841890 days apartLibreNMS before 26.7.0 Stored XSS via Oxidized API
    36Monitor
  • CVE-2026-841920 days apartLibreNMS before 26.3.1 Stored XSS via SNMP/Syslog Data
    28Monitor
  • CVE-2025-55296379 days apartLibreNMS allows stored XSS in Alert Template name field
    25Monitor
  • CVE-2025-65013287 days apartLibreNMS vulnerable to Reflected Cross-Site Scripting (XSS) in endpoint `/maps/nodeimage` parameter `Image Name`
    24Monitor
  • CVE-2025-62411320 days apartStored XSS in Alert Transport name field in LibreNMS
    23Monitor
  • CVE-2025-68614253 days apartLibreNMS Alert Rule API Cross-Site Scripting Vulnerability
    22Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • Administrator privileges are required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
High
Privileges required
High
User interaction
P
Scope
X

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

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Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records