CVE-2026-28496

CRITICALPre-NVD 9.49.4
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 1.9% (79th 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-2026-38455 (ENISA EUVD)Source: ENISA EUVD

9.4EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.9%CVSS: 9.4Exploit: 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. Versions prior to 0.8.0 have a Server-Side Template Injection (SSTI) vulnerability in the template rendering system. Administrators with access to features that render Twig templates (email templates, mass mail campaigns, custom payment adapters, and the string_render API endpoint) can inject arbitrary Twig expressions, leading to information disclosure and remote code execution. The vulnerability exists because Twig templates are rendered without a sandbox, allowing access to the full Twig environment, API context, and the application's dependency injection container. Version 0.8.0 patches the issue. Some workarounds are available. Audit existing email templates for suspicious Twig expressions, rotate all admin and client API tokens, and/or block external access to /api/system/* at reverse proxy/WAF to mitigate chaining with GHSA-78x5-c8gw-8279.

CVSS v3
9.4
EG Score
9.4CRITICALmedium confidence
EG Risk
43
EG Risk 43/100

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)
Severity94% × 45%
Impact severity (EG Severity): CVSS 9.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation1.9% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
1.9%
EPSS %ILE
79th
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 (9.4): severity, escalated by confirmed exploitation. This CVE's 9.4 is its impact severity (EG Severity), not escalated.

EG Severity
9.4 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
1.9% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). 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; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

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

The CVE record names the fixed release. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (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 2, 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(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 55× 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 95 of 182 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. 5 repeat rows among the latest 100 are merged into the row they repeat. The 87 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 06:38 UTCEG score recompute
  2. 2026-11-01 08:32 UTCEG score recompute
  3. 2026-10-31 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  4. 2026-10-31 10:27 UTCEG score recompute
  5. 2026-10-30 16:34 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  6. 2026-10-30 12:22 UTCEG score recompute
  7. 2026-10-29 16:33 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  8. 2026-10-29 14:18 UTCEG score recompute
  9. 2026-10-28 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  10. 2026-10-27 18:07 UTCEG score recompute
  11. 2026-10-27 16:31 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  12. 2026-10-26 20:01 UTCEG score recompute
  13. 2026-10-25 19:54 UTCEG score recompute
  14. 2026-10-25 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  15. 2026-10-25 14:38 UTCEG score recompute
  16. 2026-10-24 21:46 UTCEG score recompute
  17. 2026-10-24 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  18. 2026-10-23 23:42 UTCEG score recompute
  19. 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  20. 2026-10-23 01:06 UTCEG score recompute
  21. 2026-10-22 16:34 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  22. 2026-10-22 02:20 UTCEG score recompute
  23. 2026-10-21 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  24. 2026-10-21 04:13 UTCEG score recompute
  25. 2026-10-20 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
Show 70 more
  1. 2026-10-20 06:01 UTCEG score recompute
  2. 2026-10-19 16:31 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  3. 2026-10-19 07:54 UTCEG score recompute
  4. 2026-10-18 16:31 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  5. 2026-10-18 03:50 UTCEG score recompute
  6. 2026-10-17 16:33 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  7. 2026-10-17 06:23 UTCEG score recompute
  8. 2026-10-16 16:41 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  9. 2026-10-16 07:46 UTCEG score recompute
  10. 2026-10-15 16:31 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  11. 2026-10-15 06:45 UTCEG score recompute
  12. 2026-10-14 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  13. 2026-10-14 02:28 UTCEG score recompute
  14. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  15. 2026-10-12 22:43 UTCEG score recompute
  16. 2026-10-12 16:34 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  17. 2026-10-12 16:16 UTCEG score recompute
  18. 2026-10-11 19:58 UTCEG score recompute
  19. 2026-10-11 17:12 UTCEG score recompute
  20. 2026-10-11 14:42 UTCEG score recompute
  21. 2026-10-11 13:48 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  22. 2026-10-10 20:00 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  23. 2026-10-09 20:07 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  24. 2026-10-08 17:11 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  25. 2026-10-08 04:24 UTCOSV refresh
  26. 2026-10-07 23:47 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  27. 2026-10-06 15:17 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  28. 2026-10-05 17:42 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  29. 2026-10-04 23:21 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  30. 2026-10-03 14:25 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  31. 2026-10-01 19:49 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  32. 2026-09-30 15:03 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  33. 2026-09-28 13:51 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  34. 2026-09-26 15:58 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  35. 2026-09-26 00:26 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  36. 2026-09-20 20:15 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  37. 2026-09-18 19:27 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  38. 2026-09-18 10:29 UTCEG score recompute
  39. 2026-09-17 19:30 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  40. 2026-09-16 14:08 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  41. 2026-09-16 05:15 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  42. 2026-09-14 02:06 UTCEG score recompute
  43. 2026-09-13 16:47 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  44. 2026-09-13 12:26 UTCEG score recompute
  45. 2026-09-12 15:01 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  46. 2026-09-11 14:52 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  47. 2026-09-10 09:34 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  48. 2026-09-08 22:00 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  49. 2026-09-07 16:01 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  50. 2026-09-06 13:47 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  51. 2026-09-04 05:06 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  52. 2026-09-02 14:11 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  53. 2026-09-01 13:53 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  54. 2026-09-01 04:39 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  55. 2026-08-30 20:27 UTCEG score recompute
  56. 2026-08-30 19:17 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  57. 2026-08-30 01:22 UTCEPSS rescoreEPSS 1.9% · 77th percentile
  58. 2026-08-28 21:41 UTCEPSS rescoreEPSS 1.9% · 77th percentile
  59. 2026-08-27 14:25 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  60. 2026-08-26 14:46 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  61. 2026-08-25 13:49 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  62. 2026-08-24 22:12 UTCEG score recompute
  63. 2026-08-24 14:17 UTCEPSS rescoreEPSS 1.9% · 78th percentile
  64. 2026-08-24 13:54 UTCEG score recompute
  65. 2026-08-22 00:48 UTCEG score recompute
  66. 2026-08-21 23:49 UTCEPSS rescoreEPSS 18% · 96th percentile
  67. 2026-08-20 23:37 UTCEG score recompute
  68. 2026-08-20 22:55 UTCEPSS rescoreEPSS 18% · 96th percentile
  69. 2026-08-20 07:47 UTCEG score recompute
  70. 2026-08-19 17:03 UTCEPSS rescoreEPSS 18% · 96th percentile

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-2026-28496.yaml
    Published Jun 24, 2026

    FOSSBilling - Server-Side Template Injection

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-28496?
CVE-2026-28496 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. Versions prior to 0.8.0 have a Server-Side Template Injection (SSTI) vulnerability in the template rendering system. Administrators with access to features that render Twig templates (email templates, mass mail campaigns,…
When was the CVE record for CVE-2026-28496 published?
The CVE record for CVE-2026-28496 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-2026-28496 actively exploited?
CVE-2026-28496 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.9% probability of exploitation in the next 30 days (79th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-28496?
CVE-2026-28496 has a CVSS base score of 9.4 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-28496?
The CVE record for CVE-2026-28496 names the fix: "Version 0.8.0 patches the issue."

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