Vikunja has an iCalendar Property Injection via CRLF in CalDAV Task Output

published 2026-04-10 6 mo ago modified 2026-10-26 13 d ago also GHSA-2g7h-7rqr-9p4r , GO-2026-4951 , EUVD-2026-21428

cvss: 4.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 distros 1 links 2

go code.vikunja.io/api 2.3.0
vikunja vikunja 2.3.0

govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

github.com/go-vikunja/vikunja#2580 pull request
github.com/go-vikunja/vikunja/releases/tag/v2.3.0 release

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 6 mo ago (2026-04-13)

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2g7h-7rqr-9p4r referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
GitHub	3.1	4.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
go	code.vikunja.io/api	<2.3.0 all versions	2.3.0

Affected products

go-vikunja vikunja

Classification

Weakness

CWE-93 Improper Neutralization of CRLF Sequences

References

github.com /go-vikunja/vikunja/pull/2580
web, issue-tracking
github.com /go-vikunja/vikunja/security/advisories/GHSA-2g7h-7rqr-9p4r
exploit, web, vendor-advisory, advisory
github.com /go-vikunja/vikunja/releases/tag/v2.3.0
web, release-notes
nvd.nist.gov /vuln/detail/CVE-2026-35601
advisory
github.com /go-vikunja/vikunja
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary