# CVE-2026-35601: Vikunja has an iCalendar Property Injection via CRLF in CalDAV Task Output

> Attackers can inject arbitrary iCalendar properties into CalDAV task outputs via CRLF injection in task titles, potentially altering client behavior.

- **Severity:** Medium 4.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 10 Apr 2026
- **Updated:** 13 Apr 2026
- **Also known as:** GHSA-2g7h-7rqr-9p4r, GO-2026-4951

## What is CVE-2026-35601?

CVE-2026-35601 is a medium-severity vulnerability in go-vikunja vikunja, published on 10 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the CalDAV output generator builds iCalendar VTODO entries via raw string concatenation without applying RFC 5545 TEXT value escaping. User-controlled task titles containing CRLF characters break the iCalendar property boundary, allowing injection of arbitrary iCalendar properties such as ATTACH, VALARM, or ORGANIZER. This vulnerability is fixed in 2.3.0.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences)

## Which versions are affected by CVE-2026-35601?

3 open source packages ship an affected version, including code.vikunja.io/api. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `code.vikunja.io/api` | Go | All versions | None |
| `code.vikunja.io/api` | Go | All versions | 2.3.0 |
| `code.vikunja.io/api` | Go | All versions | 2.3.0 |

Products: Vikunja Vikunja.

## How do I fix CVE-2026-35601?

Upgrade code.vikunja.io/api to 2.3.0 or later.

## Is CVE-2026-35601 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-35601 exists.

## Other vulnerabilities in go-vikunja vikunja

- [CVE-2026-28268](https://insights.sbomify.com/CVE-2026-28268/): Vikunja Vulnerable to Account Takeover via Password Reset Token Reuse (critical 9.8)
- [CVE-2026-27575](https://insights.sbomify.com/CVE-2026-27575/): Vijkunja has Weak Password Policy Combined with Persistent Sessions After Password Change (critical 9.1)
- [CVE-2026-25935](https://insights.sbomify.com/CVE-2026-25935/): Vikunja Affected by XSS Via Task Preview (high 8.6)
- [CVE-2026-35595](https://insights.sbomify.com/CVE-2026-35595/): Vikunja Affected by Privilege Escalation via Project Reparenting (high 8.3)
- [CVE-2026-33316](https://insights.sbomify.com/CVE-2026-33316/): Vikunja’s Improper Access Control Enables Bypass of Administrator-Imposed Account Disablement (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-35601 and fix it if it is affected.

What it is: CVE-2026-35601 is a medium-severity vulnerability in go-vikunja vikunja, published on 10 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-35601 exists.

Affected packages and fixed versions:
- code.vikunja.io/api (Go): affected all versions; no fix listed
- code.vikunja.io/api (Go): affected all versions; fixed in 2.3.0
- code.vikunja.io/api (Go): affected all versions; fixed in 2.3.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-35601/ (Markdown: https://insights.sbomify.com/CVE-2026-35601/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35601
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35601
- OSV: https://osv.dev/vulnerability/CVE-2026-35601

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-35601/
Summaries are generated and may contain mistakes; the official description above is the record.