Vulnerability in Adminer (CVE-2026-16434)
Summary
Vulnerability in Adminer (CVE-2026-16434). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.5.1 or later.
Original description
The description as published by the source.
Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-16434 has been found in Adminer.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Adminer to 5.5.1 or later.
If unsure, ask your IT team or search "Adminer CVE-2026-16434" on the vendor's site.
CVE-2026-16434 (Adminer) — CWE-20
Patched: 5.5.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-20) exists in Adminer.
Check the vendor advisory for the affected versions of Adminer.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 5.5.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Adminer' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'Adminer' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Adminerを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Adminer to 5.5.1ステージング環境で 5.5.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2026-16434 adminer
References
- web github.com
- web disclosure@vulncheck.com
- web nvd.nist.gov
- web github.com