CVE-2026-76216 — Vikunja through 2.4.0 Principal-Type Confusion via LinkSharing

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HIGH

Vikunja through 2.4.0 Principal-Type Confusion via LinkSharing

Published Aug 19, 2026

7.7

HIGH

CVSS 4.0

EPSS 0.36%

Description

Vikunja through 2.4.0 contains a principal-type confusion vulnerability where LinkSharing principals with id N are treated as user principals with users.id == N at three permission checks lacking type guards. Attackers with a link-share JWT can remove victims from teams, enumerate and delete victim bot users, or read team rosters by exploiting id collisions in the autoincrement space.

Affected products

Vendor GO-Vikunja Product Vikunja Default
unaffected
- Version
  0
  Status
  affected
  Constraints
  <=2.4.0

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

GO-Vikunja

Vikunja

unaffected

Version	Status	Constraints
0	affected	<=2.4.0

Remediation

No remediation recorded yet.

Metrics

0.36% 0.00363

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.

EPSS probability 0.00363

Score over time

Aug–Oct 2026

EPSS v5

Percentile over time

EPSS v5

Table of values (2 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 1, 2026	0.36% (0.00363)	27.73th	v5 (v2026.06.15)
Aug 20, 2026	0.26% (0.00264)	18.44th	v5 (v2026.06.15)

Weaknesses (1)

CWE-639

Authorization Bypass

References (2)

https://github.com/go-vikunja/vikunja/security/advisories/GHSA-32r8-5843-4qw2
vendor-advisory
https://www.vulncheck.com/advisories/vikunja-through-principal-type-confusion-via-linksharing
third-party-advisory

Link	Providers	Tags
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-32r8-5843-4qw2		vendor-advisory
https://www.vulncheck.com/advisories/vikunja-through-principal-type-confusion-via-linksharing		third-party-advisory