CVE-2026-26279: Froxlor has Admin-to-Root Privilege Escalation via Input Validation Bypass + OS Command Injection

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 1.2%, percentile 67: FIRST’s model estimates a 1.2% chance of exploitation activity in the next 30 days, higher than 67% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Needs an account (high (admin)). Exposure depends on who can log in.
• Only applies if your dependency tree includes froxlor/froxlor (Composer (PHP)) <= 2.3.3, fixed in 2.3.4. Check your lockfile, including transitive dependencies.

What it is

Froxlor is open source server administration software. Prior to 2.3.4, a typo in Froxlor's input validation code (== instead of =) completely disables email format checking for all settings fields declared as email type. This allows an authenticated admin to store arbitrary strings in the panel.adminmail setting. This value is later concatenated into a shell command executed as root by a cron job, where the pipe character | is explicitly whitelisted. The result is full root-level Remote Code Execution. This vulnerability is fixed in 2.3.4.

From the GitHub advisory

Summary

A typo in Froxlor's input validation code (== instead of =) completely disables email format checking for all settings fields declared as email type. This allows an authenticated admin to store arbitrary strings — including shell metacharacters — in the panel.adminmail setting. This value is later concatenated into a shell command executed as root by a cron job, where the pipe character | is explicitly whitelisted. The result is full root-level Remote Code Execution.

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Why This Is a Security Vulnerability (Not Just "Admin Using Admin Features")

Froxlor is a shared hosting control panel. In production deployments:

Weakness type: CWE-78, CWE-482.

Product: froxlor/froxlor (Composer (PHP)) · Assigned by: GitHub_M · Published: 2026-03-03

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: high (admin)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.17% probability of exploitation activity in the next 30 days; percentile 67.

Timeline

• 2026-03-03 — CVE record published by GitHub_M
• 2026-03-03 — GitHub-reviewed advisory GHSA-33mp-8p67-xj7c published (critical)
• 2026-03-04 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-33mp-8p67-xj7c github.com
2. CVE.org record CVE-2026-26279 cve.org
3. NVD entry CVE-2026-26279 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest