Browser extension injects prompt into every Claude and ChatGPT message
Summary
Extension uses a content script to prepend a hidden instruction to every user prompt before submission. The injected preamble reshapes the AI's behavior across all of the user's conversations.
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.
(?i)(?:input\.value|textContent)\s*=\s*(?:"[^"]{10,}"|\`[^\`]{10,}\`)\s*\+
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_000096
{
meta:
source = "jiffy-intel"
severity = "high"
description = "Auto-generated from Jiffy Intel indicators"
strings:
$content_pattern_0 = "(?i)(?:input\\.value|textContent)\\s*=\\s*(?:\"[^\"]{10,}\"|\\`[^\\`]{10,}\\`)\\s*\\+"
condition:
$content_pattern_0
}Auto-generated from the indicators above. Adapt syntax for your detection stack before deploying.
Affected tools
| Tool | Versions | Status |
|---|---|---|
| Chrome / Chromium | * | vulnerable |
| ChatGPT (GPT Store) | * | 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.
- Smart Prompt HelperExtensionRemoved
- AI SuperpowersExtensionUnder review
- Prompt BoosterExtensionQuarantined
How to remediate
- 01Audit extensions with host permissions on AI sites.
- 02Check for content-script manipulation of prompt fields.
Timeline & sources
Timeline
- First observedMar 5, 20261 month ago
- Last updatedApr 24, 2026today
- PublishedMar 19, 202629 days ago
Sources
References
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