# CVE-2026-123497: Vikunja veans before 2.7.1 HTTPS to HTTP Downgrade in Server Discovery

Status: published. Published: 2026-11-08. Updated: 2026-11-10.

Vikunja veans before 2.7.1 contains a protocol downgrade vulnerability in serverCandidates that allows on-path attackers to force plain HTTP during veans init and login. Attackers can block HTTPS ports so discovery accepts an unverified HTTP response, capturing passwords, TOTP codes or bot tokens and persisting cleartext API traffic.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- go-vikunja / vikunja (code.vikunja.io/veans): ≥ 0; < 2.7.1 (affected, semver); 2.7.1 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 7.6 (high); CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 6.8 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N; source: CNA: VulnCheck

- CVSS 4.0: 7.6 (high); CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 6.8 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.16% as of 2026-11-10; percentile 4.99%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-319

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-wqw2-rgwv-99qx (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/vikunja-veans-before-2.7.1-https-to-http-downgrade-in-server-discovery (CNA: VulnCheck; third-party-advisory)

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-wqw2-rgwv-99qx (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/vikunja-veans-before-2.7.1-https-to-http-downgrade-in-server-discovery (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123497; retrieved 2026-11-10; source updated 2026-11-10

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123497; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-123497; retrieved 2026-11-10; source updated Not reported

Revision: c60494a448fb106e907fac96291e49dbb05fe2076372827586a83ccd30dadae2

Canonical: https://y2.dev/cve/CVE-2026-123497

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.