CVE-2026-57439

MEDIUMCVSS 5/10EPSS 0.09%

Last modified

CVE-2026-57439 is a medium-severity vulnerability rated 5/10 on the CVSS scale. 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. EPSS estimates a 0.09% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
5/10

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability
0.09%

0.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
gchqCyberChef< 11.2.0

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-57439?
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.
How severe is CVE-2026-57439?
CVE-2026-57439 has a CVSS score of 5/10 (MEDIUM severity). The EPSS model estimates a 0.09% probability of exploitation in the next 30 days.
How do I fix CVE-2026-57439?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST