v2board / Xboard Authentication Token Exposure via loginWithMailLink
Summary
| CVE | CVE-2026-39912 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-09 19:16:25 UTC |
| Updated | 2026-04-09 19:16:25 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 9.1 CRITICAL from [email protected]
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-201 | CWE-201 CWE-201 Insertion of Sensitive Information Into Sent Data
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 9.1 | CRITICAL | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 9.1 | CRITICAL | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N |
| 3.1 | [email protected] | Primary | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| 3.1 | CNA | CVSS | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
PresentPrivileges Required
NoneUser Interaction
NoneConfidentiality
HighIntegrity
HighAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | V2board | V2board | affected 1.6.1 1.7.4 semver | Not specified |
| CNA | V2board | V2board | affected bdb10bed32c5f37df2f0872c3cb354e9b7a293bd 0ca47622a50116d0ddd7ffb316b157afb57d25e8 git | Not specified |
| CNA | Cedar2025 | Xboard | affected 0.1.9 semver | Not specified |
| CNA | Cedar2025 | Xboard | unaffected 121511523f04882ec0c7447acd9b8ebcb8a47957 git | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8... | [email protected] | github.com | |
| github.com/v2board/v2board/pull/981 | [email protected] | github.com | |
| github.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957 | [email protected] | github.com | |
| github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660b... | [email protected] | github.com | |
| chocapikk.com/posts/2026/xboard-v2board-account-takeover | [email protected] | chocapikk.com | |
| www.vulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-l... | [email protected] | www.vulncheck.com | |
| github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660b... | [email protected] | github.com | |
| github.com/cedar2025/Xboard/pull/873 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Valentin Lobstein (Chocapikk) (en)
There are currently no legacy QID mappings associated with this CVE.