CVE-2025-71407
CRITICALCVE-2025-71407 is a critical-severity (CVSS 9.8) Out-of-bounds Write vulnerability. O3 Security confirms whether CVE-2025-71407 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Nokogiri before 1.18.3 contains a stack buffer overflow vulnerability in libxml2 when reporting DTD validation errors with long QName prefixes, and a use-after-free vulnerability during…
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-71407.
Description
Nokogiri before 1.18.3 contains a stack buffer overflow vulnerability in libxml2 when reporting DTD validation errors with long QName prefixes, and a use-after-free vulnerability during validation against untrusted XML Schemas. Attackers can trigger these vulnerabilities by providing malicious DTD content or untrusted XSD files to cause denial of service or potential code execution.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2025-71407 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-71407 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-71407. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-71407 in your dependencies?
O3 detects CVE-2025-71407 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.