GHSA-c3m8-x3cg-qm2c
Configuration Override in helmet-csp
Versions of helmet-csp before to 2.9.1 are vulnerable to a Configuration Override affecting the application's Content Security Policy (CSP). The package's browser sniffing for Firefox deletes the default-src CSP policy, which is the fallback policy. This allows an attacker to remove an application's default CSP, possibly rendering the application vulnerable to Cross-Site Scripting.
Recommendation
Upgrade to version 2.9.1 or later. Setting the browserSniff configuration to false in vulnerable versions also mitigates the issue.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
What each source reports
GitHub Advisories Score used
Configuration Override in helmet-csp
Versions of helmet-csp before to 2.9.1 are vulnerable to a Configuration Override affecting the application's Content Security Policy (CSP). The package's browser sniffing for Firefox deletes the default-src CSP policy, which is the fallback policy. This allows an attacker to remove an application's default CSP, possibly rendering the application vulnerable to Cross-Site Scripting.
Recommendation
Upgrade to version 2.9.1 or later. Setting the browserSniff configuration to false in vulnerable versions also mitigates the issue.
- Record
GHSA-c3m8-x3cg-qm2c- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N - Updated
- 2026-11-02
OSV
Configuration Override in helmet-csp
Versions of helmet-csp before to 2.9.1 are vulnerable to a Configuration Override affecting the application's Content Security Policy (CSP). The package's browser sniffing for Firefox deletes the default-src CSP policy, which is the fallback policy. This allows an attacker to remove an application's default CSP, possibly rendering the application vulnerable to Cross-Site Scripting.
Recommendation
Upgrade to version 2.9.1 or later. Setting the browserSniff configuration to false in vulnerable versions also mitigates the issue.
- Record
GHSA-c3m8-x3cg-qm2c- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N - Updated
- 2026-11-02
Affected packages
| Package | Affected | Fixed |
|---|---|---|
helmet-cspnpm | 1.2.2 up to 2.9.1 | 2.9.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | GitHub Advisories, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
GHSA-c3m8-x3cg-qm2c is a medium vulnerability (CVSS 6.5) in helmet-csp, published September 3, 2020. No source lists public exploit code. Fixed in helmet-csp 2.9.1.