Unrestricted File Upload in kunstmaan/media-bundle (CVE-2026-104890)
Summary
Vulnerability in kunstmaan/media-bundle (CVE-2026-104890). Successful exploitation can lead to full system takeover. Exploitable via webshell.pHp. Mitigation: upgrade to 7.3.2 or later.
Original description
The description as published by the source.
Summary
The MediaBundle blocks dangerous upload extensions with a blacklist that was matched
case-sensitively, while the stored filename was lowercased afterwards. A file uploaded
as webshell.pHp therefore bypassed the blacklist and was written to the web-accessible
upload directory as webshell.php, where the web server executed it. Any authenticated
backend user with access to the media section could obtain remote code execution.
Details
FileHandler::getFilePath() rewrote blacklisted extensions to .txt using a
case-sensitive regex, and only then lowercased the extension when building the stored
name — so the check ran against the attacker-controlled casing and the normalisation
happened after it.
Two further weaknesses contributed:
- The default blacklist contained only
phpandhtaccess, leaving other
server-executable extensions (phtml,php5,phar,shtml,cgi, …) unblocked
regardless of casing. - Configured blacklist values were interpolated into the regex unescaped.
Impact
An authenticated user with access to the admin media section can upload a file that the
web server executes as PHP. The uploaded file is reachable over HTTP without
authentication, giving arbitrary code execution as the web server user.
Patches
Fixed in kunstmaan/media-bundle 7.3.2. The extension is now normalised before it is
checked and compared with in_array(); the default blacklist is expanded to the full
set of server-executable extensions; and a…
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-2026-104890 has been found in kunstmaan/media-bundle.
Attackers can target a specific entry point like webshell.pHp over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 7.2/10.
What to do: upgrade kunstmaan/media-bundle to 7.3.2 or later.
If unsure, ask your IT team or search "kunstmaan/media-bundle CVE-2026-104890" on the vendor's site.
CVE-2026-104890 (kunstmaan/media-bundle) — CWE-434 / CVSS v3 7.2
Attack vector: remote (network-reachable) / no user interaction
Attack surface: webshell.pHp / webshell.php / php / htaccess
Patched: 7.3.2 — 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-434) exists in kunstmaan/media-bundle. Attackers reach the vulnerable code path via webshell.pHp.
Check the vendor advisory for the affected versions of kunstmaan/media-bundle. Attack surface: webshell.pHp / webshell.php / php / htaccess.
Severity: High (CVSS 7.2/10). Successful exploitation can lead to full system takeover.
Update to 7.3.2.
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 'kunstmaan/media-bundle' . 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
-
1Identify exposure identify
grep -r 'kunstmaan/media-bundle' . | 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
kunstmaan/media-bundle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 kunstmaan/media-bundle to 7.3.2ステージング環境で 7.3.2 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。