# Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover

Advisory record · `GHSA-xv7q-fvmc-jx96`

- **Identifiers:** `GHSA-xv7q-fvmc-jx96` · `CVE-2026-62367` · `GO-2026-6758`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **Weakness (CWE):** [CWE-287](https://cwe.mitre.org/data/definitions/287.html) · [CWE-290](https://cwe.mitre.org/data/definitions/290.html) · [CWE-345](https://cwe.mitre.org/data/definitions/345.html)
- **Tags:** [Authentication bypass](https://agentprime.io/advisories/tag/auth-bypass.md) · [CWE-345](https://agentprime.io/advisories/tag/cwe-345.md)
- **Published:** 9 Oct 2026
- **Updated:** 19 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 9 Oct 2026, 20:49 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `code.vikunja.io/api` (Go): affected `>=1.0.0, <2.4.0`; fixed in `2.4.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Vikunja versions from 1.0.0 before 2.4.0 are affected when the per-provider OIDC emailfallback option is enabled. An unauthenticated attacker who can get the configured identity provider to issue a token with a victim's email address can log in as a local account holder without the password and gain a full session, though TOTP-enabled users are protected. Upgrade to Vikunja 2.4.0 or later. The source gives no workaround besides disabling emailfallback, which is the default.

Written 1 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 7.5 High, CVSS 4.0: `CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0009, the 1st percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:11 UTC: First seen by agentprime
- 31 Oct 2026, 14:11 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-xv7q-fvmc-jx96)

## Sources

- [GitHub Advisory Database: GHSA-xv7q-fvmc-jx96](https://github.com/advisories/GHSA-xv7q-fvmc-jx96)
- [OSV: GHSA-xv7q-fvmc-jx96](https://osv.dev/vulnerability/GHSA-xv7q-fvmc-jx96)
- <https://github.com/go-vikunja/vikunja/security/advisories/GHSA-xv7q-fvmc-jx96>
- <https://github.com/go-vikunja/vikunja/commit/7854f2729ab72000210b61c25929678fd6901630>
- <https://github.com/go-vikunja/vikunja>
- <https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-xv7q-fvmc-jx96>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-xv7q-fvmc-jx96/>. Everything for agents: <https://agentprime.io/llms.txt>.