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A GitHub-reviewed security advisory, not necessarily under active exploitation the way our CISA KEV advisories are, but a real, disclosed vulnerability in an open-source dependency.
Affected packages
Vulnerable: < 11.2.0
Patched in 11.2.0
Details
On 5 June 2026 CyberChef received a security vulnerability report from @hyuunnn detailing a vulnerability in the Series Chart operation, where malicious input could result in prototype pollution of the data structures outputted from the operation. Other operations following Series Chart could have their behaviour manipulated by the attacker-controlled prototype, for example, injecting malicious content into their HTML output.
In this case, a demonstration was provided that chained the Series Chart operation with the Parse UDP operation to cause attacker controlled JavaScript to be executed.
When the Series Chart operation parses user-supplied CSV, it accepts __proto__ as a key and uses it to pollute the object.
The objToTbale function in src/core/lib/Protocol.mjs, used in a number of IP parsing operations, renders data items within <td> tags without escaping.
These bugs can be chained to produce an XSS vulnerability.
Encoded input data is:
__proto__,<img src=x onerror=alert(document.domain)>,1
Objects with attacker controlled prototypes could be processed by CyberChef operations. This enabled control of the output of some operations, and in particular, the ability to insert malicious JavaScript into the output of the Parse UDP operation.
This has been patched in release v11.2.0.
No workarounds are available. Users must upgrade to CyberChef v11.2.0.
EPSS, exploit probability
Low0.14%
estimated chance of real-world exploitation in the next 30 days, higher than 3.0% of every CVE FIRST.org scores
Refreshed 11/9/2026, via FIRST.org's EPSS model, not CVSS, this measures likelihood of exploitation, not how severe it would be.
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