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CVE-2026-76216 high CVSS 7.5

Vulnerability in code.vikunja.io/api (CVE-2026-76216)

Summary

Vulnerability in code.vikunja.io/api (CVE-2026-76216). Successful exploitation can lead to full system takeover. Exploitable via DELETE /api/v1/teams/{T}/members/{username}.

Original description

The description as published by the source.

Summary

Vikunja's web.Auth interface (pkg/web/web.go, single method GetID() int64) is satisfied by BOTH *user.User and *models.LinkSharing. A link-share's GetID() returns the raw positive share.ID (pkg/models/link_sharing.go:83-85), which lives in the same positive autoincrement ID space as users.id. The safe negated form getUserID() = share.ID * -1 (link_sharing.go:126-128) exists but is NOT used at three permission sinks. As a result, a link-share principal with id N — which should have zero authority over teams or bot users — is treated as the user whose users.id == N at three permission checks that lack the a.(*LinkSharing) guard their sibling methods have. This is the same principal-type-confusion class as CVE-2026-68581 (GHSA-vvcv-vpph-h844), but at three code paths that advisory/fix never touched.

Root Cause

web.Auth is a one-method interface (GetID() int64). *LinkSharing.GetID() returns the raw positive share id. Three permission methods compare this raw id directly and omit the link-share type guard used elsewhere in the same files:

  1. TeamMember.CanDelete (pkg/models/team_members_permissions.go:31-40): the self-removal fast path if u.ID == a.GetID() { return true } (:36) executes before IsAdmin. IsAdmin (:48-51) is the ONLY place that rejects link shares (if _, is := a.(*LinkSharing); is { return false }, :50) — and it is never reached when the fast path returns true.
  2. BotUser.isOwner (`pkg/…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-76216 has been found in code.vikunja.io/api.
Attackers can target a specific entry point like DELETE /api/v1/teams/{T}/members/{username} over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 7.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "code.vikunja.io/api CVE-2026-76216" on the vendor's site.

CVE-2026-76216 (code.vikunja.io/api) — CWE-639 / CVSS v3 7.5
Attack vector: remote (network-reachable) / no user interaction
Attack surface: DELETE /api/v1/teams/{T}/members/{username} / GET /api/v1/user/bots / DELETE /api/v1/user/bots/{id} / GET /api/v1/teams/{T}
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-639) exists in code.vikunja.io/api. Attackers reach the vulnerable code path via DELETE /api/v1/teams/{T}/members/{username}.

📍 Affected scope

Check the vendor advisory for the affected versions of code.vikunja.io/api. Attack surface: DELETE /api/v1/teams/{T}/members/{username} / GET /api/v1/user/bots / DELETE /api/v1/user/bots/{id} / GET /api/v1/teams/{T}.

🔥 Severity

Severity: High (CVSS 7.5/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual DELETE /api/v1/teams/{T}/members/{username} requests with malformed payloads or SQL meta-characters. Run grep -r 'code.vikunja.io/api' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'code.vikunja.io/api' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で code.vikunja.io/api を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Hunt for indicators of compromise detect 
    grep 'DELETE /api/v1/teams/{T}/members/{username}' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで DELETE /api/v1/teams/{T}/members/{username} への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Post-deployment verification verify 
    Replay attack against DELETE /api/v1/teams/{T}/members/{username} on staging to confirm patch closes the vector

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

go code.vikunja.io/api
[{"type":"SEMVER","events":[{"introduced":"0"},{"last_affected":"2.4.0"}]}]

References

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