CVE-2026-27604

CRITICALPre-NVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 67% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
10.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 10.0Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

FOSSBilling is a free, open-source billing and client management system. Starting in version 0.5.4 and prior to version 0.8.0, an authorization bypass in the API role handling allows unauthenticated access to privileged /api/system/* endpoints. Because system resolves to the cron admin identity, attackers can invoke admin API methods without valid credentials, session, or CSRF token. Version 0.8.0 patches the issue. Some workarounds are available. Block external access to /api/system/* at reverse proxy/WAF, restrict API access by trusted source IPs only (api.allowed_ips), rotate all admin/client API tokens immediately, invalidate active sessions and reset high-privilege credentials, and/or review API request logs for suspicious /api/system/ access and treat as potential incident.

CVSS v3
10.0
EG Score
10.0(medium)
EPSS
32.9%
KEV
Not listed

Published

June 23, 2026

Last Modified

June 23, 2026

Advisory Details (3)

Auto-updated Jul 7, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

CVE-2026-28496 - FOSSBilling Auth Bypass and Twig SSTI to Unauthenticated RCE | Blog | VulnCheck

https://www.vulncheck.com/blog/fossbilling-auth-bypass-ssti-rce
github Patch Available

Improper API role validation (system) enables unauthenticated access to privileged admin functions · Advisory · FOSSBilling/FOSSBilling · GitHub

https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-78x5-c8gw-8279
github Patch Available🟡 PoC Available

Server-side template injection in Twig template rendering enables information disclosure and RCE · Advisory · FOSSBilling/FOSSBilling · GitHub

https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-57mv-jm88-66jc

Weakness Classification(4)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 49× in last 7d / 149× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 149 total refreshes for this CVE.

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Frequently asked(5)

What is CVE-2026-27604?
CVE-2026-27604 is a critical vulnerability published on June 23, 2026. FOSSBilling is a free, open-source billing and client management system. Starting in version 0.5.4 and prior to version 0.8.0, an authorization bypass in the API role handling allows unauthenticated access to privileged /api/system/ endpoints. Because system resolves to the cron admin identity,…
When was CVE-2026-27604 disclosed?
CVE-2026-27604 was first published in the National Vulnerability Database on June 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27604 actively exploited?
CVE-2026-27604 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 32.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-27604?
CVE-2026-27604 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2026-27604?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27604, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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