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CVE-2026-54271 high CVSS 8.2

Code Injection in protobufjs-cli (CVE-2026-54271)

Summary

Code injection in protobufjs-cli (CVE-2026-54271). Confidential information can be exposed externally. Exploitable via pbjs. Mitigation: upgrade to 2.5.0 or later.

Original description

The description as published by the source.

Summary

A previous fix for unsafe name handling in pbjs static / static-module code generation was incomplete. Affected versions of protobufjs-cli could still emit unsafe JavaScript references when generating static output from crafted JSON descriptor input. The common case of parsing schemas from .proto files is not affected.

This is a bypass of GHSA-6r35-46g8-jcw9 / CVE-2026-44295.

Impact

An attacker who can provide or influence pre-parsed JSON descriptors passed to pbjs static code generation may be able to cause generated JavaScript output to contain attacker-controlled code.

The injected code may execute if the generated file is later executed or imported and an affected generated API path is invoked.

Preconditions

  • The application or build process must run pbjs static code generation on a pre-parsed JSON descriptor influenced by an attacker.
  • The generated JavaScript file must subsequently be executed or imported.
  • An affected generated API path must be invoked.

Workarounds

Do not run affected versions of pbjs static or static-module generation on untrusted JSON descriptors. If untrusted JSON descriptors must be accepted, validate descriptor-derived names before code generation and reject names that could not have been produced by parsing a valid .proto file. Running code generation in an isolated environment can reduce impact.

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-2026-54271 has been found in protobufjs-cli.
Attackers can target a specific entry point like pbjs over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.2/10.
What to do: upgrade protobufjs-cli to 2.5.0 or later.
If unsure, ask your IT team or search "protobufjs-cli CVE-2026-54271" on the vendor's site.

CVE-2026-54271 (protobufjs-cli) — CWE-94 / CVSS v3 8.2
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: pbjs
Patched: 2.5.0 — apply immediately
Workaround: Do not run affected versions of pbjs static or static-module generation on untrusted JSON descriptors.
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.

❓ What is the problem

Arbitrary code execution (CWE-94) exists in protobufjs-cli. Attackers reach the vulnerable code path via pbjs without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of protobufjs-cli. Attack surface: pbjs.

🔥 Severity

Severity: High (CVSS 8.2/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 2.5.0.

🛡️ Workaround

Workaround: Do not run affected versions of pbjs static or static-module generation on untrusted JSON descriptors.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'protobufjs-cli' . 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

  1. 1
    Identify exposure identify 
    grep -r 'protobufjs-cli' . | 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 protobufjs-cli を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply temporary workaround mitigate 
    Do not run affected versions of `pbjs` static or static-module generation on untrusted JSON descriptors.

    パッチが適用されるまでの応急処置として、Do not run affected versions of pbjs static or static-module generation on untrusted JSON descriptors. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade protobufjs-cli to 2.5.0

    ステージング環境で 2.5.0 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。

  4. 4
    Post-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

npm protobufjs-cli
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.5.0"}]}]

References

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