8.7

CVE-2026-91973: go-vikunja vikunja

CVSS: 8.7v4.0HighDeferred
AliasesGHSA-m469-88xx-8rx2GO-2026-6737
Published 15-09-2026Last modified 15-09-2026
Open JSON

Vulnerability summary

CVE-2026-91973 is a high (CVSS 8.7) vulnerability in go-vikunja vikunja. EPSS estimates a 0.67% chance of exploitation in the next 30 days, higher than 51.4% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.7/10
010
High · v4.0 (CVE.org)
EPSS score
0.67%
0%100%
Low · +0.06 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 authentication bypass vulnerability in CalDAV BasicAuth endpoints that lack rate limiting protection. Remote unauthenticated attackers can issue unbounded credential-guessing requests against /dav, /.well-known, and /feeds routes to bypass the instance's anti-brute-force controls and compromise password-only accounts.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.67%

Chance of exploitation in the next 30 days

Percentile

51%

Versus all other CVEs

30-day change

+0.06 pp

From 0.61% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.67%

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< 2.6.0 | All versions (No fix recorded)
Go-vikunja1 product

2 vendors · 2 products

References

6 links