MCP server leaks GITHUB_TOKEN via error messages
Summary
MCP server that, on error paths, includes the full environment in a verbose traceback returned to the agent. GitHub tokens and other secrets surface in the tool response body and are then cached in agent logs.
Severity & confidence
High
Credible abuse path with meaningful impact on confidentiality, integrity, or availability. Remediate on a short timeline; do not wait for the next sprint cycle.
Confirmed
Observed directly by Jiffy scanners or validated by multiple independent sources. Indicators are reliable enough to drive automated action.
Indicators
Observed patterns and artifacts associated with this entry. Each indicator can be copied into your detection stack or SIEM.
(?is)traceback[\s\S]{0,500}(?:GITHUB_TOKEN|GH_TOKEN|API_KEY)
Detection rule
A YARA-style pseudo-rule auto-generated from the indicators above. Useful as a starting point — adapt the syntax for your target detection platform.
rule jiffy_ti_2026_000050
{
meta:
source = "jiffy-intel"
severity = "high"
description = "Auto-generated from Jiffy Intel indicators"
strings:
$content_pattern_0 = "(?is)traceback[\\s\\S]{0,500}(?:GITHUB_TOKEN|GH_TOKEN|API_KEY)"
condition:
$content_pattern_0
}Auto-generated from the indicators above. Adapt syntax for your detection stack before deploying.
Affected tools
| Tool | Versions | Status |
|---|---|---|
| Any MCP-capable agent | * | vulnerable |
Example artifacts
Sanitized examples of artifacts Jiffy has observed exhibiting this pattern. Publisher handles are redacted; version ranges and status reflect the most recent scan.
- gh-helpers-mcpMCP serverStill live
- repo-tools-mcpMCP serverUnder review
How to remediate
- 01Sanitize error payloads in MCP servers.
- 02Redact any env variable names matching secret patterns before returning errors.
Timeline & sources
Timeline
- First observedMar 3, 20261 month ago
- Last updatedApr 20, 2026today
- PublishedMar 15, 20261 month ago
Sources
References
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