Vulnerability in Nokogiri (CVE-2019-5477)

Summary

Vulnerability in Nokogiri (CVE-2019-5477). Successful exploitation can lead to full system takeover. Exploitable via Kernel.open.

Original description

The description as published by the source.

A command injection vulnerability in Nokogiri v1.10.3 and earlier allows commands to be executed in a subprocess via Ruby's Kernel.open method. Processes are vulnerable only if the undocumented method Nokogiri::CSS::Tokenizer#load_file is being called with unsafe user input as the filename. This vulnerability appears in code generated by the Rexical gem versions v1.0.6 and earlier. Rexical is used by Nokogiri to generate lexical scanner code for parsing CSS queries. The underlying vulnerability was addressed in Rexical v1.0.7 and Nokogiri upgraded to this version of Rexical in Nokogiri v1.10.4.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

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-2019-5477 has been found in Nokogiri.
Attackers can target a specific entry point like Kernel.open over the network to misuse the product.
Successful exploitation can lead to full system takeover.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Nokogiri CVE-2019-5477" on the vendor's site.

CVE-2019-5477 (Nokogiri)
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Kernel.open
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

A vulnerability (unclassified) exists in Nokogiri. Attackers reach the vulnerable code path via Kernel.open without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of Nokogiri. Attack surface: Kernel.open.

🔥 Severity

Severity: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Nokogiri' . 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
Identify exposure identify
```
grep -r 'Nokogiri' . | 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 Nokogiri を grep し、稼働しているサービス・バージョンを把握する。
2
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。

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2019-5477 rexical Fixed in: 1.0.7-1

References

advisory github.com
advisory lists.debian.org
advisory lists.debian.org
advisory lists.debian.org
advisory security.gentoo.org
advisory usn.ubuntu.com
patch github.com
report hackerone.com