critical CVSS 9.1

CVE-2026-26988·PHP vulnerability

LibreNMS is an auto-discovering PHP/MySQL/SNMP based network monitoring tool. Versions 25.12.0 and below contain an SQL Injection vulnerability in the ajax_table.php endpoint. The application fails to properly sanitize or parameterize user input when processing IPv6 address searches. Specifically, the address parameter is split into an address and a prefix, and the prefix portion is directly concatenated into the SQL query string without validation. This allows an attacker to inject arbitrary SQL commands, potentially leading to unauthorized data access or database manipulation. This issue has been fixed in version 26.2.0.

Severity
critical
Software
PHP
Fixed in
26.2.0
Published
2026-02-20

Affected versions

Until: 26.2.0

Fixed in: 26.2.0

How to fix this CVE

Upgrade LibreNMS to version 26.2.0 or later to patch the SQL injection vulnerability in the ajax_table.php endpoint that affects IPv6 address parameter handling. Organizations running affected versions should prioritize this update immediately, as the vulnerability allows attackers to execute arbitrary SQL queries and access sensitive network monitoring data without authentication.

sudo dnf update librenms

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET /ajax_table\.php\?.*address=[^\s]*['"%;(\-\-)|/\*|xp_|sp_]

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Block or rate-limit requests to ajax_table.php containing SQL metacharacters in the 'address' parameter. Implement a rule that inspects the address parameter for single quotes, double quotes, semicolons, comment markers (-- or /*), and SQL keywords (UNION, SELECT, INSERT, UPDATE, DELETE). Whitelist only valid IPv6 address formats (e.g., ^[0-9a-fA-F:]+(/[0-9]{1,3})?$).

How to check if you are affected

  1. Step 1: Check the installed LibreNMS version with: php -r "require '/opt/librenms/config.php'; echo LIBRENMS_VERSION;" or grep 'version' in /opt/librenms/includes/defines.inc.php
  2. Step 2: Verify if ajax_table.php is accessible by testing: curl -s http://localhost/ajax_table.php?address=::1 and check for 200 or 403 responses
  3. Step 3: Search web server logs for SQL error patterns in ajax_table.php requests: grep -E "ajax_table\.php.*address=.*['\"%;]" /var/log/apache2/access.log or /var/log/nginx/access.log
  4. Step 4: After upgrading, confirm the new version with: php -r "require '/opt/librenms/config.php'; echo LIBRENMS_VERSION;" and verify it is >= 26.2.0

FAQ

What is CVE-2026-26988?

CVE-2026-26988 is a critical SQL injection flaw in LibreNMS versions up to 25.12.0 where the IPv6 address prefix parameter in ajax_table.php is concatenated directly into SQL queries without sanitization, enabling attackers to execute arbitrary database commands.

Is CVE-2026-26988 being actively exploited?

No, CVE-2026-26988 is not currently listed on the CISA Known Exploited Vulnerabilities catalog, and no public exploit code is available. However, the critical CVSS score and unauthenticated attack vector warrant immediate patching.

What versions of LibreNMS are affected by CVE-2026-26988?

All versions of LibreNMS up to and including 25.12.0 are vulnerable. The vulnerability is fixed in version 26.2.0 and later.

How do I check if my server is vulnerable to CVE-2026-26988?

Run: php -r "require '/opt/librenms/config.php'; echo LIBRENMS_VERSION;" and compare the version number against 26.2.0. If it is 25.12.0 or lower, the server is vulnerable.

Does Defensia detect CVE-2026-26988?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If LibreNMS is installed on a monitored server, CVE-2026-26988 will appear in your dashboard with remediation steps.

Related PHP CVEs

CVE-2026-28289CVSS 10FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. A patch bypass vulnerability for CVE-2026-27636 in FreeScout 1.8.206 and earlier allows any authenticated user with file upload permissions to achieve Remote Code Execution (RCE) on the server by uploading a malicious .htaccess file using a zero-width space character prefix to bypass the security check. The vulnerability exists in the sanitizeUploadedFileName() function in app/Http/Helper.php. The function contains a Time-of-Check to Time-of-Use (TOCTOU) flaw where the dot-prefix check occurs before sanitization removes invisible characters. This vulnerability is fixed in 1.8.207.
CVE-2025-46348CVSS 10YesWiki is a wiki system written in PHP. Prior to version 4.5.4, the request to commence a site backup can be performed and downloaded without authentication. The archives are created with a predictable filename, so a malicious user could create and download an archive without being authenticated. This could result in a malicious attacker making numerous requests to create archives and fill up the file system, or by downloading the archive which contains sensitive site information. This issue has been patched in version 4.5.4.
CVE-2025-47916CVSS 10Invision Community 5.0.0 before 5.0.7 allows remote code execution via crafted template strings to themeeditor.php. The issue lies within the themeeditor controller (file: /applications/core/modules/front/system/themeeditor.php), where a protected method named customCss can be invoked by unauthenticated users. This method passes the value of the content parameter to the Theme::makeProcessFunction() method; hence it is evaluated by the template engine. Accordingly, this can be exploited by unauthenticated attackers to inject and execute arbitrary PHP code by providing crafted template strings.
CVE-2025-25174CVSS 10Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion') vulnerability in beeteam368 BeeTeam368 Extensions beeteam368-extensions allows PHP Local File Inclusion.This issue affects BeeTeam368 Extensions: from n/a through <= 1.9.4.
CVE-2025-62521CVSS 10ChurchCRM is an open-source church management system. Prior to version 5.21.0, a pre-authentication remote code execution vulnerability in ChurchCRM's setup wizard allows unauthenticated attackers to inject arbitrary PHP code during the initial installation process, leading to complete server compromise. The vulnerability exists in `setup/routes/setup.php` where user input from the setup form is directly concatenated into a PHP configuration template without any validation or sanitization. Any parameter in the setup form can be used to inject PHP code that gets written to `Include/Config.php`, which is then executed on every page load. This is more severe than typical authenticated RCE vulnerabilities because it requires no credentials and affects the installation process that administrators must complete. Version 5.21.0 patches the issue.

References

Track CVEs across your fleet automatically

Defensia scans your Linux servers and tells you exactly which ones are running vulnerable versions — including CVE-2026-26988. Free for 1 server.

Get started free