How severe is CVE-2026-42615?

CVE-2026-42615 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-42615 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42615?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42615 have an EU (EUVD) identifier?

Yes. CVE-2026-42615 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26191.

When was CVE-2026-42615 published?

CVE-2026-42615 was published on 2026-04-29 and last updated on 2026-06-17.

CVE-2026-42615

CVE-2026-42615 is a high-severity vulnerability with a CVSS 3.x base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 3.x base score 7.2)
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-26191
Weakness: CWE-79
Published: 2026-04-29
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is 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.
How severe is CVE-2026-42615?: CVE-2026-42615 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-42615 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-42615?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42615 have an EU (EUVD) identifier?: Yes. CVE-2026-42615 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26191.
When was CVE-2026-42615 published?: CVE-2026-42615 was published on 2026-04-29 and last updated on 2026-06-17.

References

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