Cyber Resilience

CVE-2026-35601

Vikunja ≤ 2.3.0

Public PoC
Published
10 April 2026
Modified
17 April 2026
Patch / advisory
View advisory
CVSS Score v3.1 4.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
EPSS Score 0.0020 10th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-35601 is a medium-severity CRLF Injection (CWE-93) vulnerability in Vikunja Vikunja. Its CVSS base score is 4.1 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 10th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-15 (Information Output Filtering) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

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…

more

boundary, allowing injection of arbitrary iCalendar properties such as ATTACH, VALARM, or ORGANIZER. This vulnerability is fixed in 2.3.0.

CWE(s)
CWE-93

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

CRLF injection in CalDAV/iCalendar generator of public-facing task app directly enables exploitation of the application via crafted task titles.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-33675Same product: Vikunja Vikunja
CVE-2026-40103Same product: Vikunja Vikunja
CVE-2026-33700Same product: Vikunja Vikunja
CVE-2026-25935Same product: Vikunja Vikunja
CVE-2026-33316Same product: Vikunja Vikunja
CVE-2026-28268Same product: Vikunja Vikunja
CVE-2026-27116Same product: Vikunja Vikunja
CVE-2026-34727Same product: Vikunja Vikunja
CVE-2026-33668Same product: Vikunja Vikunja
CVE-2026-33678Same product: Vikunja Vikunja

Affected Assets

vikunja
vikunja
≤ 2.3.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SI-15 Information Output Filtering
  • SI-2 Flaw Remediation
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V4.2.4

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match
prevent

Requires validation and sanitization of user-supplied task titles before they are used in CalDAV iCalendar output, directly blocking CRLF injection.

SI-15 Information Output Filtering good match
prevent

Mandates filtering/escaping of information in generated output (iCalendar VTODO properties) to neutralize untrusted content and prevent property injection.

SI-2 Flaw Remediation partial match
prevent

Requires timely remediation of the identified flaw in the CalDAV generator, ensuring the RFC 5545 escaping fix from 2.3.0 is applied.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require input neutralization and validation to block CRLF injection.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
detects

Security testing can detect CRLF flaws but does not itself implement the neutralization.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and output encoding that directly prevents CRLF injection.

A.8.26 Application security requirements partial match
prevents

Application security requirements include rules for neutralizing special characters such as CRLF in inputs.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles encourage safe handling of untrusted data but do not prescribe specific CRLF controls.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly require neutralization of CRLF sequences, fully addressing this weakness.

References