Security readout for executives and security teams
Plain-English summary
Vikunja versions before 2.0.0 allowed very weak passwords and did not end existing login sessions after a password change. If an account was guessed or reused from another breach, an attacker could stay logged in even after the user reset the password. Version 2.0.0 contains a fix.
Executive priority
Treat as urgent for any exposed Vikunja deployment. The issue enables durable account takeover when weak or reused passwords are present, but public sources do not confirm active exploitation.
Technical view
CVE-2026-27575 affects go-vikunja/vikunja before 2.0.0. The issue combines CWE-521 weak password requirements with CWE-613 insufficient session expiration. The CVSS 3.1 score is 9.1, network exploitable with no privileges or user interaction, impacting confidentiality and integrity. Public sources identify 2.0.0 as fixed.
Likely exposure
Self-hosted Vikunja instances running versions earlier than 2.0.0 are affected. Exposure is higher where the service is internet-accessible or users reuse passwords from other services.
Exploitation context
The source bundle does not cite active exploitation, and the CVE is not marked KEV. Practical risk comes from brute-force or credential-stuffing compromise followed by session persistence after password reset.
Researcher notes
Evidence is limited to the CVE record, GitHub advisory, and 2.0.0 release note. No exploit publication or KEV listing is cited. Validate fixes through version checks and session-expiration behavior without sharing offensive procedures.
Mitigation direction
- Upgrade Vikunja to version 2.0.0 or later.
- Review the GitHub advisory and Vikunja changelog for deployment guidance.
- Force password changes for users with weak or reused passwords.
- Review suspicious account activity where weak credentials may have existed.
- Consider invalidating active sessions during remediation, following vendor guidance.
Validation and detection
- Inventory all Vikunja deployments and confirm their running version.
- Flag any instance running a version earlier than 2.0.0.
- Confirm password policy behavior after upgrading in a test environment.
- Confirm password changes invalidate prior sessions after applying the fix.
- Review authentication logs for unusual access patterns.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-521: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-613: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-27575 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N3.95.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-3ccg-x393-96v8CVE reference · x_refsource_CONFIRM
- https://vikunja.io/changelog/vikunja-v2.0.0-was-releasedCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Weak Password Requirements
Weak Password Requirements represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Insufficient Session Expiration
Insufficient Session Expiration represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.