# CVE-2026-63771: Adminer < 5.4.3 Cookie Injection via X-Forwarded-Prefix Header

> Attackers can bypass SameSite cookie protections in Adminer by injecting values via the X-Forwarded-Prefix header, enabling cross-origin authenticated requests.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 20 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-63771, GHSA-c533-9qwm-8w5h, GHSA-hvv2-8jpj-gr8h, UBUNTU-CVE-2026-63771

## What is CVE-2026-63771?

CVE-2026-63771 is a medium-severity vulnerability in vrana adminer, published on 20 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Adminer before 5.4.3 contains a cookie injection vulnerability that allows attackers to manipulate cookie attributes by injecting arbitrary values through the unsanitized X-Forwarded-Prefix HTTP header used in Set-Cookie path attributes. Attackers can exploit a misconfigured reverse proxy to downgrade SameSite protection and enable cross-origin authenticated requests, bypassing cookie security controls.

Weakness: CWE-113 (Improper Neutralization of CRLF Sequences in HTTP Headers)

## Which versions are affected by CVE-2026-63771?


## How do I fix CVE-2026-63771?

Upgrade to a fixed version.

## Is CVE-2026-63771 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63771 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63771 and fix it if it is affected.

What it is: CVE-2026-63771 is a medium-severity vulnerability in vrana adminer, published on 20 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63771 exists.

Affected product: vrana adminer. 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-2026-63771/ (Markdown: https://insights.sbomify.com/CVE-2026-63771/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63771
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63771
- OSV: https://osv.dev/vulnerability/CVE-2026-63771

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63771/
Summaries are generated and may contain mistakes; the official description above is the record.