Cyberdudebivash

What is CVE-2025-9556?

Product / Vendor: Langchaingo (an AI prompt processing tool) using the gonja library v1.5.3. NVD+1
Vulnerability type: Server-Side Template Injection (SSTI) when parsing prompts that allow Jinja2 “include” or “extends” syntax. Gonja supports “include” / “extends” which allow reading arbitrary files. NVD+1
Exploit vector: Remote, network-accessible, no authentication required, no user interaction. OpenCVE

Attackers can embed template directives in prompts that exploit inclusion or extension syntax, which gonja executes, allowing file system reads. Example: reading sensitive files like /etc/passwd. NVD+1

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 Severity & Impact

Metric	Value
CVSS v3.1 Base Score	9.8 (CRITICAL) OpenCVE+1
Vector String	AV:N / AC:L / PR:N / UI:N / S:U / C:H / I:H / A:H → Network exploitable, low complexity, no privileges, no user interaction, high confidentiality/integrity/availability impact. OpenCVE
Affected version	Langchaingo versions using gonja v1.5.3 syntax with include/extends features. OpenCVE+1

Impacts include:

• Confidentiality breach: reading sensitive files (password files, configs)
• Integrity violation: manipulating templates or injected files may lead to tampering
• Availability compromise: possible Denial-of-Service (DoS) if template processing loops or resource exhaustion

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 Timeline & Disclosure

• Published / Made public: ~September 12, 2025. OpenCVE+1
• Advisory: GHSA-mgcj-g55g-rf6h on GitHub; relevant patches under PR #1348. OpenCVE+1

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 Mitigation Strategies & Immediate Remediation

1. Update / Patch
   • Upgrade to a version of Langchaingo/gonja where this vulnerability is fixed. Check the security advisory and use the fixed version from the associated GHSA advisory. OpenCVE
2. Disable or Restrict Include/Extends Syntax
   • If new version not available, disable or restrict features that allow include / extends in templates or prompts.
3. Input Sanitization & Template Isolation
   • Validate and sanitize any user-controllable parts of prompts.
   • Use sandboxing or context restrictions.
4. Least Privilege File Permissions
   • Ensure the application runs with minimal file system permissions (disallow access to sensitive directories like /etc).
5. Monitoring & Logging
   • Monitor template rendering logs. Look for unusual template instructions or errors referencing file reading.
   • Alert on attempts to use include/extends when not expected.
6. Web Application Firewall / WAF Rules
   • Create rules to block or inspect template syntax in prompt input (e.g. Jinja2 syntax markers).
7. Incident Response Plan
   • If exploit suspected, isolate instances, revoke credentials, rotate any related secrets, audit file accesses.

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 Broader Context & Why It Matters

• SSTI vulnerabilities are often devastating because templates can give attackers capacity to traverse file systems or execute code. This kind of flaw in tools that parse user input (or prompt input) is increasingly dangerous in generative AI / prompt-driven products.
• As more tools allow “include” / “extends” or other dynamic template features, similar vulnerabilities in gonja, Nunjucks, Jinja2 etc., are likely to appear.
• The attack aligns with known CWE patterns: CWE-94 (Improper Control of Generation of Code) or CWE-91 (XML / Template Injection), and CWE-200 (Exposure of Sensitive Information).
• Regulatory implications: leaks of /etc/passwd or other sensitive files may entail data protection concerns, privacy breaches, and compliance violations in many jurisdictions.

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 Recommendations (CyberDudeBivash View)

• If you’re using any prompt / AI system that leverages template engines (especially with include or extends capabilities), audit them immediately for gonja v1.5.3 or older.
• For developers, avoid template features that allow file references unless strictly needed. Use simpler engines, disable “include/extends” if safe.
• Security teams should add SSTI to their threat model when evaluating AI-prompt tools.
• Conduct fuzz testing and template injection testing for AI tools before deployment.
• Ensure prompt systems are containerized / sandboxed with restricted file system access.

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 Affiliate Blocks

•  [Template Injection Detection Toolkits]
•  [Secure Prompt Engineering Frameworks]
• [Training in AI Security / SSTI Prevention]
•  [Audit / Penetration Testing Services]

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CVE-2025-9556 Alert

Header:  CyberDudeBivash Threat Intel
Main Title: CVE-2025-9556: Critical SSTI Vulnerability in Langchaingo / Gonja v1.5.3
Highlights 

•  Server-Side Template Injection
•  No Auth Required, Remote Over Network
•  Can Read “etc/passwd” & Sensitive Files
•  Update to Fixed Version / Patch Now

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