5.3

CVE-2026-91983: go-vikunja vikunja Incorrect Authorization

CVSS: 5.3v4.0MediumDeferred
AliasesGHSA-9rg3-v78m-26q8GO-2026-6726
Published 15-09-2026Last modified 15-09-2026
Open JSON

Vulnerability summary

CVE-2026-91983 is a medium (CVSS 5.3) Incorrect Authorization vulnerability in go-vikunja vikunja. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.9% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.30%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 15-09-2026
    PublishedVulnerability first disclosed.
  2. 15-09-2026
    Last modifiedVulnerability information updated.

Description

Vikunja before 2.6.0 contains an API token scope bypass vulnerability in task read endpoints where authorization fails to inspect query string parameters. Attackers with limited token scopes can use the expand parameter to access restricted data like comments, reactions, and time entries without proper permission verification.

CVSS metrics

5 scores · 3 sources · 2 versions

EPSS trend

Probability

0.30%

Chance of exploitation in the next 30 days

Percentile

22%

Versus all other CVEs

30-day change

+0.04 pp

From 0.27% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.30%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Code.vikunja.io1 product
  • api≥ 1.0.0, < 2.6.0 | All versions (No fix recorded)
Go-vikunja1 product

2 vendors · 2 products

References

7 links