CVE-2026-39912

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

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

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-04-09. A secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this weekElevated

Also known asEUVD-2026-21043 (ENISA EUVD) · GHSA-83h9-46h8-whf4 (GitHub Security Advisories)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.1Exploit: Public PoCExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

V2Board 1.6.1 through 1.7.4 and Xboard through 0.1.9 expose authentication tokens in HTTP response bodies of the loginWithMailLink endpoint when the login_with_mail_link_enable feature is active. Unauthenticated attackers can POST to the loginWithMailLink endpoint with a known email address to receive the full authentication URL in the response, then exchange the token at the token2Login endpoint to obtain a valid bearer token with complete account access including admin privileges.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
72
EG Risk 72/100

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)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (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: An upstream fix is merged but not yet in a tagged release. 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 until it ships, then apply the release.
EPSS PROB
0.6%
EPSS %ILE
48th
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 (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-30). 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, Track* at medium and Attend at high mission impact.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, Track* at medium and Attend at high mission impact.

An upstream fix is merged but not yet in a tagged release. 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 until it ships, then apply the release.

Exploitation public PoC (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

April 9, 2026

Last Modified

October 26, 2026

Advisory Details (8)

Auto-updated Sep 16, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
Web page

v2board / Xboard Authentication Token Exposure via loginWithMailLink | Advisories | VulnCheck

https://www.vulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-loginwithmaillink
GitHub pull request

Fix: CVE-2026-39912 - Magic link token leak in loginWithMailLink

Upstream fix in progress (PR #981 · v2board/v2board, state=open)

https://github.com/v2board/v2board/pull/981
Web page

v2board/app/Http/Controllers/Passport/AuthController.php at 0ca47622a50116d0ddd7ffb316b157afb57d25e8 · v2board/v2board · GitHub

https://github.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8/app/Http/Controllers/Passport/AuthController.php#L71
GitHub pull request

Fix: CVE-2026-39912 - Magic link token leak in loginWithMailLink

Fix merged in cedar2025/Xboard PR #873 on 2026-04-09 — awaiting tagged release

https://github.com/cedar2025/Xboard/pull/873
GitHub commit

commit 121511523f04 (cedar2025/Xboard)

Fix landed in cedar2025/Xboard commit 121511523f04 — awaiting tagged release

https://github.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957
Web page

Xboard/app/Services/Auth/MailLinkService.php at 1fe6531924cc1ec662a88b9ef725afcf78d660bc · cedar2025/Xboard · GitHub

https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Services/Auth/MailLinkService.php#L49
Web page

Xboard/app/Http/Controllers/V1/Passport/AuthController.php at 1fe6531924cc1ec662a88b9ef725afcf78d660bc · cedar2025/Xboard · GitHub

https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Http/Controllers/V1/Passport/AuthController.php#L51
Web page

Xboard / V2Board: Magic Link Token Leak - Unauthenticated Account Takeover - Chocapikk's Cybersecurity Blog

https://chocapikk.com/posts/2026/xboard-v2board-account-takeover/

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 23× in last 7d / 71× 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 99 of 299 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. 1 repeat row among the latest 100 is merged into the row it repeats. The 200 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-30 19:00 UTCEG score recompute
  2. 2026-10-30 19:00 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  3. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  4. 2026-10-29 17:00 UTCEG score recompute
  5. 2026-10-29 17:00 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  6. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  7. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  8. 2026-10-28 14:59 UTCEG score recompute
  9. 2026-10-28 14:59 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  10. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  11. 2026-10-27 12:52 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  12. 2026-10-26 21:27 UTCEG score recompute
  13. 2026-10-26 21:27 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  14. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  15. 2026-10-26 02:53 UTCEG score recompute
  16. 2026-10-26 02:53 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  17. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  18. 2026-10-25 14:31 UTCEG score recompute
  19. 2026-10-25 00:51 UTCEG score recompute
  20. 2026-10-25 00:51 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  21. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  22. 2026-10-23 22:51 UTCEG score recompute
  23. 2026-10-23 22:51 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  24. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-10-22 20:43 UTCEG score recompute
Show 74 more
  1. 2026-10-22 20:43 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  2. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  3. 2026-10-21 18:39 UTCEG score recompute
  4. 2026-10-21 18:39 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  5. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  6. 2026-10-20 16:39 UTCEG score recompute
  7. 2026-10-20 16:39 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  8. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  9. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  10. 2026-10-19 14:38 UTCEG score recompute
  11. 2026-10-19 14:37 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  12. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  13. 2026-10-18 12:37 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  14. 2026-10-18 03:43 UTCEG score recompute
  15. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  16. 2026-10-17 10:35 UTCEG score recompute
  17. 2026-10-17 10:35 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  18. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  19. 2026-10-16 08:35 UTCEG score recompute
  20. 2026-10-16 08:35 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  21. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  22. 2026-10-15 06:33 UTCEG score recompute
  23. 2026-10-15 06:33 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  24. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-10-14 02:13 UTCEG score recompute
  26. 2026-10-14 02:13 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  27. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  28. 2026-10-12 22:32 UTCEG score recompute
  29. 2026-10-12 22:32 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  30. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  31. 2026-10-12 16:10 UTCEG score recompute
  32. 2026-10-12 08:08 UTCGHSA enrichmentGHSA-83h9-46h8-whf4 · GitHub severity CRITICAL · GitHub CVSS 9.1
  33. 2026-10-11 19:52 UTCEG score recompute
  34. 2026-10-11 17:05 UTCEG score recompute
  35. 2026-10-11 14:32 UTCEG score recompute
  36. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  37. 2026-10-11 09:44 UTCOSV refresh
  38. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  39. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  40. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  41. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  42. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  43. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  44. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  45. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  46. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  47. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  48. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  49. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  50. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  51. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  52. 2026-09-21 22:15 UTCOSV refresh
  53. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  54. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  55. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  56. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  57. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  58. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  59. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  60. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  61. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  62. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  63. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  64. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  65. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  66. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  67. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  68. 2026-09-02 18:08 UTCOSV refresh
  69. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  70. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  71. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  72. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  73. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  74. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.6% · 45th percentile

Publicly available exploits

(1 reference)

Public exploit code is referenced for this CVE (1 GitHub PoC). The fix is not yet in a release, so defenders should restrict or isolate affected systems accordingly until it ships.

  • GitHub PoCChocapikk/CVE-2026-39912
    Published Apr 9, 2026

    Xboard / V2Board Unauth Account Takeover - Magic Link Token Leak (CVE-2026-39912)

    Open source ↗

Frequently asked(5)

What is CVE-2026-39912?
CVE-2026-39912 is a critical-severity vulnerability; its CVE record was published on April 9, 2026. V2Board 1.6.1 through 1.7.4 and Xboard through 0.1.9 expose authentication tokens in HTTP response bodies of the loginWithMailLink endpoint when the loginwithmaillinkenable feature is active. Unauthenticated attackers can POST to the loginWithMailLink endpoint with a known email address to receive…
When was the CVE record for CVE-2026-39912 published?
The CVE record for CVE-2026-39912 was published on April 9, 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 October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-39912 actively exploited?
CVE-2026-39912 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (48th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-39912?
CVE-2026-39912 has a CVSS base score of 9.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-39912?
An upstream fix for CVE-2026-39912 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-39912

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