CVE-2026-28268: Vikunja Vulnerable to Account Takeover via Password Reset Token Reuse

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.9%, percentile 60: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 60% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes code.vikunja.io/api (Go) <= 0.24.6, no fixed version listed. Check your lockfile, including transitive dependencies.

What it is

Vikunja is an open-source self-hosted task management platform. Versions prior to 2.1.0 have a business logic vulnerability exists in the password reset mechanism of vikunja/api that allows password reset tokens to be reused indefinitely. Due to a failure to invalidate tokens upon use and a critical logic bug in the token cleanup cron job, reset tokens remain valid forever. This allows an attacker who intercepts a single reset token (via logs, browser history, or phishing) to perform a complete, persistent account takeover at any point in the future, bypassing standard authentication controls. Version 2.1.0 contains a patch for the issue.

From the GitHub advisory

Summary A critical business logic vulnerability exists in the password reset mechanism of vikunja/api that allows password reset tokens to be reused indefinitely. Due to a failure to invalidate tokens upon use and a critical logic bug in the token cleanup cron job, reset tokens remain valid forever.

This allows an attacker who intercepts a single reset token (via logs, browser history, or phishing) to perform a complete, persistent account takeover at any point in the future, bypassing standard authentication controls.

Technical Analysis The vulnerability stems from two distinct logic errors in the pkg/user/ package that confirm the tokens are never removed.

1. Logic Error in Password Reset (No Invalidation) In pkg/user/userpasswordreset.go, the ResetPassword function successfully updates the user's password but fails to delete the reset token used to authorize the request. Instead, it attempts to delete a TokenEmailConfirm token, leaving the TokenPasswordReset active.

Vulnerable Code: pkg/user/userpasswordreset.go (Lines 36-94)

Weakness type: CWE-459, CWE-640.

Product: code.vikunja.io/api (Go) · Assigned by: GitHub_M · Published: 2026-02-27

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.91% probability of exploitation activity in the next 30 days; percentile 60.

Timeline

• 2026-02-27 — CVE record published by GitHub_M
• 2026-02-28 — GitHub-reviewed advisory GHSA-rfjg-6m84-crj2 published (critical)
• 2026-03-03 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-rfjg-6m84-crj2 github.com
2. CVE.org record CVE-2026-28268 cve.org
3. NVD entry CVE-2026-28268 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. vikunja.io vikunja.io

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