CVE-2026-87891

MEDIUMPre-NVD 6.56.5
EchelonGraph scoreMEDIUM confidence

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

Score 6.5 from GitHub Security Advisory published 2026-09-12. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory
Trending — 3 sources updated this week
6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 6.5Exploit: None knownExposed services: Not assessed

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

The CVE record's CNA (WPScan) lists Rox Appointment Booking versions before 1.2.0 as affected. No release containing a fix is confirmed on record.

The Rox Appointment Booking WordPress plugin before 1.2.0 does not perform any capability or authorization check when saving its holiday schedule, allowing unauthenticated attackers to overwrite the dates the booking system treats as unavailable, which can block legitimate bookings or open dates the site owner intended to keep closed.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
44
EG Risk 44/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity65% × 45%
The EG Score, 6.5 of 10.
Exploitation0.3% × 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 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. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.3%
EPSS %ILE
25th
KEV
Not listed

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. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

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.

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 12, 2026

Last Modified

September 14, 2026

Advisory Details (1)

Auto-updated Sep 12, 2026
No fix on record yet.
Web page

Rox Appointment Booking < 1.2.0 – Unauthenticated Holiday Schedule Modification via REST API | CVE 2026-87891 | Plugin Vulnerabilities

https://wpscan.com/vulnerability/e7f3b29e-2503-41bb-b15c-3c0ef71a3a00/

Vendor Advisories for CVE-2026-87891(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 87× 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.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  3. 2026-10-12 14:49 UTCEG score recompute
  4. 2026-10-12 09:12 UTCEG score recompute
  5. 2026-10-12 09:12 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  6. 2026-10-11 19:54 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  7. 2026-10-11 19:16 UTCEG score recompute
  8. 2026-10-11 16:33 UTCEG score recompute
  9. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  10. 2026-10-11 13:49 UTCEG score recompute
  11. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  12. 2026-10-10 19:38 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  13. 2026-10-09 21:17 UTCEG score recompute
  14. 2026-10-09 21:17 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  15. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  16. 2026-10-08 23:12 UTCEG score recompute
  17. 2026-10-08 23:11 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  18. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  19. 2026-10-08 01:06 UTCEG score recompute
  20. 2026-10-08 01:05 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  21. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  22. 2026-10-07 03:00 UTCEG score recompute
  23. 2026-10-07 03:00 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  24. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  25. 2026-10-06 04:55 UTCEG score recompute
Show 73 more
  1. 2026-10-06 04:55 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  2. 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  3. 2026-10-05 06:50 UTCEG score recompute
  4. 2026-10-05 06:50 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  5. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  6. 2026-10-04 08:45 UTCEG score recompute
  7. 2026-10-04 08:45 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  8. 2026-10-03 10:40 UTCEG score recompute
  9. 2026-10-03 10:40 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  10. 2026-10-02 12:35 UTCEG score recompute
  11. 2026-10-02 12:35 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  12. 2026-10-01 19:51 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  13. 2026-10-01 13:15 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  14. 2026-09-30 15:10 UTCEG score recompute
  15. 2026-09-30 15:10 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  16. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  17. 2026-09-29 17:04 UTCEG score recompute
  18. 2026-09-29 17:04 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  19. 2026-09-28 18:36 UTCEG score recompute
  20. 2026-09-28 18:36 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  21. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  22. 2026-09-27 19:17 UTCEG score recompute
  23. 2026-09-27 19:17 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  24. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  25. 2026-09-26 21:11 UTCEG score recompute
  26. 2026-09-26 21:11 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  27. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  28. 2026-09-25 23:07 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  29. 2026-09-25 01:01 UTCEG score recompute
  30. 2026-09-25 01:01 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  31. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  32. 2026-09-24 02:56 UTCEG score recompute
  33. 2026-09-24 02:56 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  34. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  35. 2026-09-23 04:51 UTCEG score recompute
  36. 2026-09-23 04:51 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  37. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  38. 2026-09-22 06:45 UTCEG score recompute
  39. 2026-09-22 06:45 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  40. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  41. 2026-09-21 08:41 UTCEG score recompute
  42. 2026-09-21 08:40 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  43. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  44. 2026-09-20 10:26 UTCEG score recompute
  45. 2026-09-20 10:26 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  46. 2026-09-19 12:21 UTCEG score recompute
  47. 2026-09-19 12:21 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  48. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  49. 2026-09-18 14:16 UTCEG score recompute
  50. 2026-09-18 14:16 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  51. 2026-09-17 19:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  52. 2026-09-17 16:04 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  53. 2026-09-16 17:59 UTCEG score recompute
  54. 2026-09-16 17:59 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  55. 2026-09-16 14:09 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  56. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  57. 2026-09-15 19:23 UTCEG score recompute
  58. 2026-09-15 19:23 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  59. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  60. 2026-09-14 21:18 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  61. 2026-09-14 12:37 UTCEG score recompute
  62. 2026-09-14 12:37 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  63. 2026-09-13 16:48 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  64. 2026-09-13 14:28 UTCEG score recompute
  65. 2026-09-13 14:28 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7 · GitHub CVSS 6.5
  66. 2026-09-12 16:23 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7
  67. 2026-09-12 15:34 UTCEG score recomputeFirst assessed: 6.5 MEDIUM
  68. 2026-09-12 15:34 UTCGHSA enrichmentGHSA-82fg-m2x5-cqp7
  69. 2026-09-12 15:33 UTCMITRE cvelistV5CVSS v3 → 6.5 · severity → MEDIUM
  70. 2026-09-12 15:02 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  71. 2026-09-12 06:20 UTCNVD update
  72. 2026-09-12 06:14 UTCEG score recompute
  73. 2026-09-12 06:13 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-87891?
CVE-2026-87891 is a medium-severity vulnerability; its CVE record was published on September 12, 2026. The Rox Appointment Booking WordPress plugin before 1.2.0 does not perform any capability or authorization check when saving its holiday schedule, allowing unauthenticated attackers to overwrite the dates the booking system treats as unavailable, which can block legitimate bookings or open dates…
When was the CVE record for CVE-2026-87891 published?
The CVE record for CVE-2026-87891 was published on September 12, 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 14, 2026; the record at its source may have been updated since.
Is CVE-2026-87891 actively exploited?
CVE-2026-87891 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (25th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-87891?
CVE-2026-87891 has a CVSS v3.1 base score of 6.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-87891?
No fix for CVE-2026-87891 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 CVE record's CNA (WPScan) lists Rox Appointment Booking versions before 1.2.0 as affected. No release containing a fix is confirmed on record. The vendor advisories EchelonGraph has for CVE-2026-87891 are linked in the Vendor Advisories panel on this page.

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