VulnSocial

CVE-2026-27203Disclosure

LOWCVSS 8.3 · HIGH

Signal is active with 1 mentions in latest observed window

Immediate actions

  • Patch affected systems immediately

Recommended action window: Monitor and triage in normal cycle

NVD description

eBay API MCP Server is an open source local MCP server providing AI assistants with comprehensive access to eBay's Sell APIs. All versions are vulnerable to Environment Variable Injection through the updateEnvFile function. The ebay_set_user_tokens tool allows updating the .env file with new tokens. The updateEnvFile function in src/auth/oauth.ts blindly appends or replaces values without validating them for newlines or quotes. This allows an attacker to inject arbitrary environment variables into the configuration file. An attacker can inject arbitrary environment variables into the .env file. This could lead to configuration overwrites, Denial of Service, and potential RCE. There was no fix for this issue at the time of publication.

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0.5/ 10 priority

Sources & remediation

Other references
Weakness type (CWE)
CWE-15CWE-74

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

AVAILABLE

Momentum

STABLE

Threat summary

  • Patch or workaround signal is available
  • 6 mentions across 5 observed days
  • Momentum state: stable

What's happening

  • Patch or workaround mentioned in 1 signal
  • Technical details provided in 6 signals
  • Disclosure: 5 classified signals
  • Peaked 1d ago at 2 mentions (2026-05-06); latest day: 1
  • 6 total mentions across 5 days

Deep dive

Activity timeline6 mentions / 5d
01122Mentions · 2026-02-21: 1Mentions · 2026-02-22: 1Mentions · 2026-03-24: 1Mentions · 2026-05-06: 2Mentions · 2026-05-12: 1Patch / Workaround · 2026-02-22: 1Technical Details · 2026-02-21: 1Technical Details · 2026-02-22: 1Technical Details · 2026-03-24: 1Technical Details · 2026-05-06: 2Technical Details · 2026-05-12: 102-2102-2203-2405-0605-12
Signal classification2 categories
Disclosure
583.3%
Patch
116.7%
Referenced assets4 URLs
Classification over time
DateTotalLabels
2026-02-211
Disclosure1
2026-02-221
Patch1
2026-03-241
Disclosure1
2026-05-062
Disclosure2
2026-05-121
Disclosure1
Full discourse6 posts
  • mouse@mousedevv
    Disclosure

    AI Security Daily Issue #5 just dropped — and the AI gold rush just hit a brick wall: ✅ 1 Million AI Services Exposed — Intruder scanned Ollama, self-hosted LLMs, agent platforms & MCP servers. ✅ Fresh MCP RCE — CVE-2026-27203 in eBay API MCP Server: environment variable injection = instant remote code execution. Agent tool-calling just got another easy backdoor. ✅ Indirect Prompt Injection Still King — Google NotebookLM VRP payout proves file/context attacks are live and dangerous. Full issue with technical breakdowns, action items, and ready-to-copy security prompts for vibe programmers on @prmpted !

    Post summary

    The issue reports a fresh RCE vulnerability (CVE‑2026‑27203) in eBay API MCP Server via environment variable injection, alongside notes on AI service exposure.

    10045142
    56 followersView on X
  • Capxel Security@capxel_security
    Disclosure

    Three events this week. Same root cause. 1. Vercel compromised via a third-party AI tool (Context AI): API keys, passwords, env vars exposed. 2. Braintrust breach: all customers told to rotate API keys immediately. 3. New MCP RCE vulnerability (CVE-2026-27203): remote code execution via environment variable injection in eBay's API MCP server. The pattern: AI tools granted production-level access, audited at hobby-project level. Every AI agent with API tokens is a new identity in your environment. If you can't enumerate them, you can't secure them. Intelligence-first security means knowing who's in the building before the alarm goes off.

    Post summary

    The message announces CVE-2026-27203, a remote code execution vulnerability caused by environment variable injection in eBay's MCP server, while also highlighting recent AI tool related breaches.

    0000072
    23 followersView on X
  • AI Security Guard@ai_security_10x
    Disclosure

    📝 New article: Environment Variable Injection Vulnerability in eBay API MCP Server: CVE-2026-27203 Analysis https://moltx.io/articles/6be62685-20a2-475e-9799-56be978952a1

    Post summary

    The text points to a new article that analyzes CVE-2026-27203, an environmental variable injection vulnerability in eBay's API MCP Server, but it does not provide a PoC, exploit, patch information, or evidence of active exploitation.

    0000054
    5 followersView on X
  • White Rabbitx@TheRabbitPy
    Disclosure

    🚨 CVE-2026-27203 (CVSS 8.3): eBay API MCP Server env injection via updateEnvFile(). Overwrite .env for DoS/RCE in AI tools! https://feedly.com/cve/severity/8-9?page=7

    Post summary

    The post announces CVE-2026-27203 as an environment injection flaw in eBay API with potential DoS and RCE, noting its CVSS score and target function, but provides no PoC, exploit code, active exploitation evidence, or mitigation details.

    0000078
    418 followersView on X
  • PulsePatch.io@pulsepatchio
    Patch

    An environment variable injection vulnerability impacts `eBay MCP Server` (CVE-2026-27203), potentially leading to data exposure or RCE. Patching is recommended. #infosec #APIsecurity #Injection https://www.pulsepatch.io/posts/cve-2026-27203-ebay-mcp-server-env-injection

    Post summary

    The post announces an environment variable injection vulnerability in eBay MCP Server (CVE‑2026‑27203) that could lead to data exposure or RCE, and recommends applying patches.

    0000071
    1 followersView on X
  • CVETodo@CveTodo
    Disclosure

    **CVE-2026-27203** pertains to the eBay API MCP Server, an open-source local server facilitating AI assistants with access to eBay's Sell APIs. The core issue resides in the `updateEnvFile` function within the `src/auth/oauth.ts` file, which handles updating environment variables in the `.env` configuration file via the `ebay_set_user_tokens` tool. #Cybersecurity #CVE #HighSeverity #SecurityAlert #RemoteCodeExecution #DDoS https://cvetodo.com/cve/CVE-2026-27203

    Post summary

    A newly disclosed CVE-2026-27203 affecting eBay's MCP Server’s environment variable handling, with potential RCE severity, but no public exploit, patch, or active misuse reported.

    0000044
    20 followersView on X

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