CVE-2026-77999

HIGHPre-NVD 8.78.7
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (37th 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-2026-70415 (ENISA EUVD) · GHSA-ffqf-m6vh-866w (GitHub Security Advisories)Source: ENISA EUVD

8.7EG
EchelonGraph verdictPlan mitigationNo fix is confirmed yet: check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule 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: 0.4%CVSS: 8.7Exploit: None knownExposed services: Not assessed

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

Joomla Extension - j2commerce.com - Unauthenticated PayPal callback forgery leading to order confirmation fraud in J2Store 1.0.0-3.3.21, 4.0.0-4.0.21, 4.1.0-4.1.6 - The PayPal IPN listener's signature check (_validateIPN()) accepted UNVERIFIED and any non-INVALID response as valid, made its verification request with CURLOPT_SSL_VERIFYPEER disabled, and stored its verdict in a field nothing downstream ever checked — so processing continued regardless of the outcome. Separately, the paid-amount comparison only ran when mc_gross was a positive number; omitting the field from the POST body (floatval(null) == 0) skipped the check entirely. Combined with a merchant-configured receiver_email and a sequential, enumerable order id read from the custom field, an anonymous POST was enough to move a pending order straight to CONFIRMED with no payment, or force another customer's pending order to FAILED. paypalv2.php performed no amount check under any circumstances.

CVSS
8.7
EG Score
8.7HIGHmedium confidence
EG Risk
54
EG Risk 54/100

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)
Severity87% × 45%
Impact severity (EG Severity): CVSS 8.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.4% × 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 partial (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: No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
37th
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 (8.7): severity, escalated by confirmed exploitation. This CVE's 8.7 is its impact severity (EG Severity), not escalated.

EG Severity
8.7 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). 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: 14 days if the affected system is publicly exposed; 60 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.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; Attend at high (mission-essential systems).

No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (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; 60 days if it is not.

No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (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

September 3, 2026

Last Modified

September 3, 2026

Advisory Details (1)

Auto-updated Sep 3, 2026
No fix on record yet.
Web page

Powerful and intuitive Joomla eCommerce. - J2Commerce

https://www.j2commerce.com/

Vendor Advisories for CVE-2026-77999(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 34× 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 its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS → 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 188 rows 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. None are among the latest 100 rows. The 88 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:57 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  2. 2026-11-12 17:52 UTCEchelonGraph re-scored
  3. 2026-11-12 17:52 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  4. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  5. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  6. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  7. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  8. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  9. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  10. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  11. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  12. 2026-11-05 04:56 UTCEchelonGraph re-scored
  13. 2026-11-05 04:56 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  14. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  15. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  16. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  17. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  18. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  19. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  20. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  21. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  22. 2026-10-28 16:00 UTCEchelonGraph re-scored
  23. 2026-10-28 16:00 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  24. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  25. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
Show 75 more
  1. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  2. 2026-10-25 14:01 UTCEchelonGraph re-scored
  3. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  4. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  5. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  6. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  7. 2026-10-20 19:49 UTCEchelonGraph re-scored
  8. 2026-10-20 19:49 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  9. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  10. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  11. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  12. 2026-10-18 03:11 UTCEchelonGraph re-scored
  13. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  14. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  15. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  16. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  17. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  18. 2026-10-13 06:53 UTCEchelonGraph re-scored
  19. 2026-10-13 06:52 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  20. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  21. 2026-10-12 15:37 UTCEchelonGraph re-scored
  22. 2026-10-11 19:23 UTCEchelonGraph re-scored
  23. 2026-10-11 16:39 UTCEchelonGraph re-scored
  24. 2026-10-11 13:57 UTCEchelonGraph re-scored
  25. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  26. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  27. 2026-10-10 11:45 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  28. 2026-10-09 23:42 UTCEchelonGraph re-scored
  29. 2026-10-09 23:41 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  30. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  31. 2026-10-09 01:34 UTCEchelonGraph re-scored
  32. 2026-10-09 01:34 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  33. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  34. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  35. 2026-10-07 23:35 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  36. 2026-10-07 02:10 UTCEchelonGraph re-scored
  37. 2026-10-07 02:10 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  38. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  39. 2026-10-06 13:39 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  40. 2026-10-06 01:37 UTCEchelonGraph re-scored
  41. 2026-10-06 01:37 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  42. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  43. 2026-10-05 13:27 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  44. 2026-10-05 01:20 UTCEchelonGraph re-scored
  45. 2026-10-05 01:20 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  46. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  47. 2026-10-04 13:18 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  48. 2026-10-04 01:09 UTCEchelonGraph re-scored
  49. 2026-10-04 01:09 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  50. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  51. 2026-10-03 12:49 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  52. 2026-10-02 19:53 UTCEchelonGraph re-scored
  53. 2026-10-02 19:53 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  54. 2026-10-02 07:51 UTCEchelonGraph re-scored
  55. 2026-10-02 07:51 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  56. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  57. 2026-10-01 19:38 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  58. 2026-10-01 07:18 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  59. 2026-09-30 19:16 UTCEchelonGraph re-scored
  60. 2026-09-30 19:16 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  61. 2026-09-30 02:58 UTCEchelonGraph re-scored
  62. 2026-09-30 02:58 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  63. 2026-09-29 15:24 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  64. 2026-09-29 08:50 UTCEchelonGraph re-scored
  65. 2026-09-29 08:50 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  66. 2026-09-28 20:48 UTCEchelonGraph re-scored
  67. 2026-09-28 20:48 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  68. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  69. 2026-09-28 05:40 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  70. 2026-09-27 17:38 UTCEchelonGraph re-scored
  71. 2026-09-27 17:38 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  72. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  73. 2026-09-27 05:35 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH
  74. 2026-09-26 17:23 UTCEchelonGraph re-scored
  75. 2026-09-26 17:23 UTCGHSA enrichmentGHSA-ffqf-m6vh-866w · GitHub severity HIGH

Frequently asked(5)

What is CVE-2026-77999?
CVE-2026-77999 is a high-severity vulnerability; its CVE record was published on September 3, 2026. Joomla Extension - j2commerce.com - Unauthenticated PayPal callback forgery leading to order confirmation fraud in J2Store 1.0.0-3.3.21, 4.0.0-4.0.21, 4.1.0-4.1.6 - The PayPal IPN listener's signature check (_validateIPN()) accepted UNVERIFIED and any non-INVALID response as valid, made its…
When was the CVE record for CVE-2026-77999 published?
The CVE record for CVE-2026-77999 was published on September 3, 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 September 3, 2026; the record at its source may have been updated since.
Is CVE-2026-77999 actively exploited?
CVE-2026-77999 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (37th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-77999?
CVE-2026-77999 has a CVSS base score of 8.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-77999?
No fix for CVE-2026-77999 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-77999 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-77999

Explore →

Is Your Infrastructure Affected by CVE-2026-77999?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.