CVE-2026-42615: CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') in GCHQ CyberChef
GCHQ CyberChef versions prior to 11. 0. 0 contain a high-severity cross-site scripting (XSS) vulnerability. This issue arises from improper neutralization of input during web page generation, specifically in the Show Base64 offsets feature. An attacker can exploit this by crafting malicious input that injects script code, potentially leading to information disclosure or session hijacking. The vulnerability has a CVSS score of 7. 2, indicating a high impact on confidentiality and integrity without requiring user interaction or privileges. No official patch or remediation guidance is currently available from the vendor. Users should monitor vendor advisories for updates and exercise caution when processing untrusted input with affected versions of CyberChef.
AI Analysis
Technical Summary
CVE-2026-42615 is a cross-site scripting (CWE-79) vulnerability in GCHQ CyberChef before version 11.0.0. The vulnerability occurs due to improper input neutralization in the Show Base64 offsets feature, allowing injection of malicious scripts via crafted input in the URL fragment. This can lead to execution of arbitrary scripts in the context of the user's browser session. The CVSS 3.1 base score is 7.2 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N), reflecting network attack vector, low attack complexity, no privileges or user interaction required, and a scope change with partial confidentiality and integrity impact. No patch or official remediation level has been published yet.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary JavaScript in the victim's browser context, potentially leading to partial confidentiality and integrity loss such as theft of sensitive information or manipulation of displayed data. There is no impact on availability. The vulnerability can be triggered remotely without authentication or user interaction.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, avoid using affected versions of CyberChef with untrusted input, especially the Show Base64 offsets feature. Implement additional input validation or sanitization on the client side if possible. Monitor official GCHQ CyberChef communications for updates.
CVE-2026-42615: CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') in GCHQ CyberChef
Description
GCHQ CyberChef versions prior to 11. 0. 0 contain a high-severity cross-site scripting (XSS) vulnerability. This issue arises from improper neutralization of input during web page generation, specifically in the Show Base64 offsets feature. An attacker can exploit this by crafting malicious input that injects script code, potentially leading to information disclosure or session hijacking. The vulnerability has a CVSS score of 7. 2, indicating a high impact on confidentiality and integrity without requiring user interaction or privileges. No official patch or remediation guidance is currently available from the vendor. Users should monitor vendor advisories for updates and exercise caution when processing untrusted input with affected versions of CyberChef.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-42615 is a cross-site scripting (CWE-79) vulnerability in GCHQ CyberChef before version 11.0.0. The vulnerability occurs due to improper input neutralization in the Show Base64 offsets feature, allowing injection of malicious scripts via crafted input in the URL fragment. This can lead to execution of arbitrary scripts in the context of the user's browser session. The CVSS 3.1 base score is 7.2 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N), reflecting network attack vector, low attack complexity, no privileges or user interaction required, and a scope change with partial confidentiality and integrity impact. No patch or official remediation level has been published yet.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary JavaScript in the victim's browser context, potentially leading to partial confidentiality and integrity loss such as theft of sensitive information or manipulation of displayed data. There is no impact on availability. The vulnerability can be triggered remotely without authentication or user interaction.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, avoid using affected versions of CyberChef with untrusted input, especially the Show Base64 offsets feature. Implement additional input validation or sanitization on the client side if possible. Monitor official GCHQ CyberChef communications for updates.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mitre
- Date Reserved
- 2026-04-29T02:55:52.684Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69f1803bcbff5d86106f825d
Added to database: 4/29/2026, 3:51:23 AM
Last enriched: 4/29/2026, 4:06:20 AM
Last updated: 4/29/2026, 8:10:20 AM
Views: 178
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