What’s Vulnerable › Vulnerabilities

CVE-2026-57439: CyberChef: Prototype pollution in Series Chart operation

• Severity: medium (CVSS 5.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-79

Description

CyberChef is a web app for encryption, encoding, compression, and data analysis. Prior to 11.2.0, the Series Chart operation accepts __proto__ as a key while parsing user-supplied CSV, allowing prototype pollution that can be chained with operations such as Parse UDP to inject malicious JavaScript into HTML output. This issue is fixed in version 11.2.0.

Affected products

• gchq CyberChef: before 11.2.0

References

• https://github.com/gchq/CyberChef/commit/85db3be5d0096859b810f0e8d3e151d5dc9b948f
• https://github.com/gchq/CyberChef/issues/2568
• https://github.com/gchq/CyberChef/pull/2569
• https://github.com/gchq/CyberChef/releases/tag/v11.2.0
• https://github.com/gchq/CyberChef/security/advisories/GHSA-fx6f-382r-j72c
• https://github.com/gchq/CyberChef/security/advisories/GHSA-fx6f-382r-j72c

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