GHSA-w5cr-2qhr-jqc5
Cloudflare Agents has a Reflected Cross-Site Scripting (XSS) vulnerability in AI Playground site
GHSA-w5cr-2qhr-jqc5 is a medium vulnerability (CVSS 6.2) in agents, published February 13, 2026. No source lists public exploit code. Fixed in agents 0.3.10.
- Severity
- 6.2 MediumCVSS 4.0, GitHub Advisories
- Exploit chance
- UnscoredNo EPSS score yet
- Exploitation
- None knownNot on CISA’s or ENISA’s lists
- Fixed in
0.3.10agents
Description
Summary
A Reflected Cross-Site Scripting (XSS) vulnerability was discovered in the AI Playground's OAuth callback handler. The error_description query parameter was directly interpolated into an HTML script tag without proper escaping, allowing attackers to execute arbitrary JavaScript in the context of the victim's session.
Root cause
The OAuth callback handler in site/ai-playground/src/server.ts directly interpolated the authError value, sourced from the error_description query parameter, into an inline <script> tag.
Impact
An attacker could craft a malicious link that, when clicked by a victim, would:
- Steal user chat message history
- Access all LLM interactions stored in the user's session.
- Access connected MCP Servers
- Interact with any MCP servers connected to the victim's session (public or authenticated/private), potentially allowing the attacker to perform actions on the victim's behalf
Mitigation:
- PR: https://github.com/cloudflare/agents/pull/841
- Agents-sdk users should upgrade to
agents@0.3.10 - Developers using
configureOAuthCallbackwith custom error handling in their own applications should ensure all user-controlled input is escaped before interpolation.
Credits
Disclosed responsibly by Nishant Kumawat
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Active
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- None
Affected packages
| Package | Affected | Fixed |
|---|---|---|
agentsnpm | before 0.3.10 | 0.3.10 |
What each source reports
GitHub Advisories Score used
Cloudflare Agents has a Reflected Cross-Site Scripting (XSS) vulnerability in AI Playground site
Summary
A Reflected Cross-Site Scripting (XSS) vulnerability was discovered in the AI Playground's OAuth callback handler. The error_description query parameter was directly interpolated into an HTML script tag without proper escaping, allowing attackers to execute arbitrary JavaScript in the context of the victim's session.
Root cause
The OAuth callback handler in site/ai-playground/src/server.ts directly interpolated the authError value, sourced from the error_description query parameter, into an inline <script> tag.
Impact
An attacker could craft a malicious link that, when clicked by a victim, would:
- Steal user chat message history
- Access all LLM interactions stored in the user's session.
- Access connected MCP Servers
- Interact with any MCP servers connected to the victim's session (public or authenticated/private), potentially allowing the attacker to perform actions on the victim's behalf
Mitigation:
- PR: https://github.com/cloudflare/agents/pull/841
- Agents-sdk users should upgrade to
agents@0.3.10 - Developers using
configureOAuthCallbackwith custom error handling in their own applications should ensure all user-controlled input is escaped before interpolation.
Credits
Disclosed responsibly by Nishant Kumawat
- Record
GHSA-w5cr-2qhr-jqc5- CVSS 4.0
- 6.2 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
Cloudflare Agents has a Reflected Cross-Site Scripting (XSS) vulnerability in AI Playground site
Summary
A Reflected Cross-Site Scripting (XSS) vulnerability was discovered in the AI Playground's OAuth callback handler. The error_description query parameter was directly interpolated into an HTML script tag without proper escaping, allowing attackers to execute arbitrary JavaScript in the context of the victim's session.
Root cause
The OAuth callback handler in site/ai-playground/src/server.ts directly interpolated the authError value, sourced from the error_description query parameter, into an inline <script> tag.
Impact
An attacker could craft a malicious link that, when clicked by a victim, would:
- Steal user chat message history
- Access all LLM interactions stored in the user's session.
- Access connected MCP Servers
- Interact with any MCP servers connected to the victim's session (public or authenticated/private), potentially allowing the attacker to perform actions on the victim's behalf
Mitigation:
- PR: https://github.com/cloudflare/agents/pull/841
- Agents-sdk users should upgrade to
agents@0.3.10 - Developers using
configureOAuthCallbackwith custom error handling in their own applications should ensure all user-controlled input is escaped before interpolation.
Credits
Disclosed responsibly by Nishant Kumawat
- Record
GHSA-w5cr-2qhr-jqc5- CVSS 4.0
- 6.2 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N - Weakness
- CWE-79
- Updated
- 2026-11-02
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | GitHub Advisories, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.