Protocol Downgrade Vulnerability in Vikunja by Vikunja
CVE-2026-123497

7.6HIGH

Key Information:

Vendor

Go-vikunja

Status
Vikunja
Vendor
CVE Published:
8 November 2026

What is CVE-2026-123497?

Vikunja veans before version 2.7.1 is susceptible to a protocol downgrade vulnerability in the serverCandidates component. This flaw enables an attacker to manipulate the initial communication phase, forcing the application to revert to an unsecured HTTP connection during user initialization and login. By obstructing HTTPS access, attackers can trick the application into accepting unverified HTTP responses. This can lead to the interception of sensitive information such as passwords, Time-based One-Time Password (TOTP) codes, and bot tokens, as well as the exposure of cleartext API traffic.

Affected Version(s)

vikunja 0 < 2.7.1

vikunja 2.7.1

References

https://github.com/go-vikunja/vikunja/security/advisories...
vendor-advisory
https://www.vulncheck.com/advisories/vikunja-veans-before...
third-party-advisory

CVSS V4

Score:
7.6
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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