[deps] Vault: Update koa to v2.16.3 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
koa (source)	2.16.2 -> 2.16.3

GitHub Vulnerability Alerts

CVE-2025-62595

Summary:

A bypass was discovered in the Koa.js framework affecting its back redirect functionality. In certain circumstances, an attacker can manipulate the Referer header to force a user’s browser to navigate to an external, potentially malicious website. This occurs because the implementation incorrectly treats some specially crafted URLs as safe relative paths. Exploiting this vulnerability could allow attackers to perform phishing, social engineering, or other redirect-based attacks on users of affected applications.

This vulnerability affects the code referenced in GitHub Advisory GHSA-jgmv-j7ww-jx2x (which is tracked as CVE‑2025‑54420).

Details:

The patched code attempts to treat values that startWith('/') as safe relative paths and only perform origin checks for absolute URLs. However, protocol‑relative URLs (those beginning with //host) also start with '/' and therefore match the startsWith('/') branch. A protocol‑relative referrer such as //evil.com with trailing double-slash is treated by the implementation as a safe relative path, but browsers interpret Location: //evil.com as a redirect to https://evil.com (or http:// based on context).
This discrepancy allows an attacker to supply Referer: //evil.com and trigger an external redirect - bypassing the intended same‑origin protection.

Proof of concept (PoC):

Affected line of code: https://github.com/koajs/koa/blob/master/lib/response.js#L326
The problematic logic looks like:

Request with a protocol‑relative Referer:
curl -i -H "Referer: //haymiz.dev" http://127.0.0.1:3000/test

Vulnerable response will contain:
HTTP/1.1 302 Found
Location: //haymiz.dev

A browser receiving that Location header navigates to https://haymiz.dev (or http:// depending on context), resulting in an open redirect to an attacker‑controlled host:

Recommendation / Patch:

• Do not treat //host as a safe relative path. Explicitly exclude protocol‑relative values from any relative‑path branch.
• Normalize the Referer by resolving it with a base (e.g., new URL(rawRef, ctx.href)), then compare resolved.origin (scheme+host+port) to ctx.origin (or ctx.host plus scheme/port) before allowing the redirect.

Impact:

An attacker who can cause a victim to visit a specially crafted link (or inject a request with a controlled Referer) can cause the victim to be redirected to an attacker‑controlled domain. This can be used for phishing, social engineering, or to bypass some protection rules that rely on same‑origin navigation.

---

Release Notes

koajs/koa (koa)

v2.16.3

Compare Source

What's Changed

• fix: normalize referer before redirect by @​fengmk2 in #​1909

Full Changelog: koajs/koa@v2.16.2...v2.16.3

---

Configuration

📅 Schedule: Branch creation - "" (UTC), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.

[bitwarden-bot]

Internal tracking:

• ID: PM-28526
• Link: https://bitwarden.atlassian.net/browse/PM-28526

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 41.25%. Comparing base (81453ed) to head (e5fe538).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #17514   +/-   ##
=======================================
  Coverage   41.25%   41.25%           
=======================================
  Files        3546     3546           
  Lines      102040   102040           
  Branches    15308    15308           
=======================================
  Hits        42099    42099           
+ Misses      58177    58176    -1     
- Partials     1764     1765    +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.