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Vulnerabilities

Vulnerability · CVE-2026-42615

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

Published Apr 29, 2026 · catalog updated Jul 24, 2026 · GCHQ CyberChef before 11.0.0

Check if you run it

No confirmed exploitation is on record for CVE-2026-42615. EPSS is 0.37%. Act only if a listed version of GCHQ CyberChef before 11.0.0 is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (GCHQ CyberChef before 11.0.0).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.37%
Remediation
Not established
Affected products
See sources for product scope

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

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-42615

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-42615. EPSS is 0.37%. Act only if a listed version of GCHQ CyberChef before 11.0.0 is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 0.37%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 29, 2026 · NIST NVD

    Detected

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

  2. Jul 24, 2026 · NIST NVD

    Updated

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

Sources

  • CVE.orgVulnerability recordCVE-2026-42615

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-42615

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-42615

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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.