Vulnerability in yiisoft/yii2 (CVE-2026-39850)
Summary
Vulnerability in yiisoft/yii2 (CVE-2026-39850). Confidential information can be exposed externally. Exploitable via require. Mitigation: upgrade to 2.0.55 or later.
Original description
The description as published by the source.
The core view rendering method View::renderPhpFile() calls extract($_params_, EXTR_OVERWRITE) before the require statement that includes the view file. A caller-controlled parameter named _file_ in the $params array overwrites the internal local variable that specifies which file is included — enabling a Local File Inclusion primitive.
Impact
- Local File Inclusion (arbitrary file read via non-PHP files)
- Potential RCE if attacker can write PHP files via a separate primitive
- Information disclosure
Patches
2.0.55
Workarounds
No.
Source: GitHub Security Advisories (Global) 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-2026-39850 has been found in yiisoft/yii2.
Attackers can target a specific entry point like require over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.4/10.
What to do: upgrade yiisoft/yii2 to 2.0.55 or later.
If unsure, ask your IT team or search "yiisoft/yii2 CVE-2026-39850" on the vendor's site.
CVE-2026-39850 (yiisoft/yii2) — CWE-20 / CVSS v3 7.4
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: require / _file_
Patched: 2.0.55 — 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 yiisoft/yii2. Attackers reach the vulnerable code path via require without authentication.
Check the vendor advisory for the affected versions of yiisoft/yii2. Attack surface: require / _file_.
Severity: High (CVSS 7.4/10). Confidential information can be exposed externally.
Update to 2.0.55.
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 'yiisoft/yii2' . 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 'yiisoft/yii2' . | 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
yiisoft/yii2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 yiisoft/yii2 to 2.0.55ステージング環境で 2.0.55 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。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web security-advisories@github.com
- web security-advisories@github.com
- web github.com
- web github.com