CVE-2026-27604

CRITICALPre-NVD 10.010.0
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 10.0 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 1.3% (69th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-38451 (ENISA EUVD)Source: ENISA EUVD

10.0EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.3%CVSS: 10.0Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

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
10.0CRITICALmedium confidence
EG Risk
61
EG Risk 61/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity100% × 45%
Impact severity (EG Severity): CVSS 10.0 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation1.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: The CVE record names the fixed release. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
1.3%
EPSS %ILE
69th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (10.0): severity, escalated by confirmed exploitation. This CVE's 10.0 is its impact severity (EG Severity), not escalated.

EG Severity
10.0 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
1.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

The CVE record names the fixed release. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 23, 2026

Last Modified

June 23, 2026

Advisory Details (3)

Auto-updated Oct 22, 2026
Fix named in the CVE record. Sources: github.
Web page

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 advisoryMentions a patch (unverified)

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 advisoryMentions a patch (unverified)

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 14× in last 7d / 48× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 97 of 185 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 3 repeat rows among the latest 100 are merged into the row they repeat. The 88 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-27 16:31 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  2. 2026-10-27 05:41 UTCEG score recompute
  3. 2026-10-26 16:31 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  4. 2026-10-25 23:57 UTCEG score recompute
  5. 2026-10-25 16:32 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  6. 2026-10-25 14:38 UTCEG score recompute
  7. 2026-10-24 22:17 UTCEG score recompute
  8. 2026-10-24 16:32 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  9. 2026-10-23 20:38 UTCEG score recompute
  10. 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  11. 2026-10-22 18:58 UTCEG score recompute
  12. 2026-10-22 16:34 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  13. 2026-10-21 17:19 UTCEG score recompute
  14. 2026-10-21 16:32 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  15. 2026-10-20 16:32 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  16. 2026-10-20 15:15 UTCEG score recompute
  17. 2026-10-19 16:31 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  18. 2026-10-19 13:34 UTCEG score recompute
  19. 2026-10-18 16:31 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  20. 2026-10-18 03:51 UTCEG score recompute
  21. 2026-10-17 16:33 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  22. 2026-10-17 10:08 UTCEG score recompute
  23. 2026-10-16 16:41 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  24. 2026-10-16 08:27 UTCEG score recompute
  25. 2026-10-15 16:31 UTCEPSS rescoreEPSS 1.3% · 69th percentile
Show 72 more
  1. 2026-10-15 06:47 UTCEG score recompute
  2. 2026-10-14 16:32 UTCEPSS rescoreEPSS 1.3% · 69th percentile
  3. 2026-10-14 02:30 UTCEG score recompute
  4. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.3% · 68th percentile
  5. 2026-10-12 22:45 UTCEG score recompute
  6. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  7. 2026-10-12 16:17 UTCEG score recompute
  8. 2026-10-11 19:59 UTCEG score recompute
  9. 2026-10-11 17:13 UTCEG score recompute
  10. 2026-10-11 14:44 UTCEG score recompute
  11. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  12. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  13. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  14. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  15. 2026-10-08 04:24 UTCOSV refresh
  16. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  17. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  18. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  19. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  20. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  21. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  22. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  23. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  24. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  25. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  26. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  27. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  28. 2026-09-18 10:29 UTCEG score recompute
  29. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  30. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  31. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  32. 2026-09-14 02:06 UTCEG score recompute
  33. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  34. 2026-09-13 12:26 UTCEG score recompute
  35. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  36. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  37. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  38. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  39. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  40. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  41. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  42. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  43. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  44. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  45. 2026-08-30 20:27 UTCEG score recompute
  46. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  47. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  48. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  49. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  50. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  51. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  52. 2026-08-24 22:12 UTCEG score recompute
  53. 2026-08-24 13:54 UTCEG score recompute
  54. 2026-08-23 03:22 UTCEG score recompute
  55. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  56. 2026-08-22 13:56 UTCEG score recompute
  57. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  58. 2026-08-21 00:36 UTCEG score recompute
  59. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  60. 2026-08-20 07:47 UTCEG score recompute
  61. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  62. 2026-08-19 04:50 UTCEG score recompute
  63. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  64. 2026-08-17 14:55 UTCEG score recompute
  65. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  66. 2026-08-16 18:36 UTCEG score recompute
  67. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  68. 2026-08-16 05:16 UTCEG score recompute
  69. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  70. 2026-08-15 04:53 UTCEG score recompute
  71. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  72. 2026-08-14 00:24 UTCEG score recompute

Public detection templates

(1 reference)

A public Nuclei detection template is referenced for this CVE. A detection template checks whether a system is affected; it is not necessarily exploit code.

  • Nucleihttp/cves/2026/CVE-2026-27604.yaml
    Recorded Oct 12, 2026

    FOSSBilling 0.5.4-0.7.x - Unauthenticated System API Role Authorization Bypass

    Open source ↗

Frequently asked(5)

What is CVE-2026-27604?
CVE-2026-27604 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-27604 published?
The CVE record for CVE-2026-27604 was published on June 23, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of June 23, 2026; the record at its source may have been updated since.
Is CVE-2026-27604 actively exploited?
CVE-2026-27604 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.3% probability of exploitation in the next 30 days (69th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-27604?
CVE-2026-27604 has a CVSS base score of 10.0 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-27604?
The CVE record for CVE-2026-27604 names the fix: "Version 0.8.0 patches the issue."

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-27604

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