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


- **Severity:** High 7.6 (`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`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 8 Nov 2026
- **Updated:** 10 Nov 2026
- **Also known as:** GHSA-rg35-8p7r-mq2v, GHSA-wqw2-rgwv-99qx

## What is CVE-2026-123497?

CVE-2026-123497 is a high-severity vulnerability in go-vikunja vikunja, published on 8 Nov 2026. 

### Official description

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.

Weakness: CWE-319 (Cleartext Transmission of Sensitive Information)

## Which versions are affected by CVE-2026-123497?


## How do I fix CVE-2026-123497?

No fix has been published for CVE-2026-123497 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-123497 being exploited?

There is no known exploitation of CVE-2026-123497 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123497 and fix it if it is affected.

What it is: CVE-2026-123497 is a high-severity vulnerability in go-vikunja vikunja, published on 8 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123497 in the wild and no public exploit code.

Affected product: go-vikunja vikunja. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-123497/ (Markdown: https://insights.sbomify.com/CVE-2026-123497/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123497
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123497
- OSV: https://osv.dev/vulnerability/CVE-2026-123497

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123497/
Summaries are generated and may contain mistakes; the official description above is the record.