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PatchSiren cyber security CVE debrief

CVE-2026-40451 DeepL CVE debrief

A medium-severity cross-site scripting vulnerability was discovered in the DeepL Chrome browser extension, affecting versions from v1.22.0 to v1.23.0. This vulnerability, tracked as CVE-2026-40451, allows an attacker to execute arbitrary script in a user's browser and inject malicious HTML into web pages viewed by the user.

Vendor
DeepL
Product
Chrome browser extension
CVSS
MEDIUM 5.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-22
Original CVE updated
2026-06-16
Advisory published
2026-04-22
Advisory updated
2026-06-16

Who should care

Users of the DeepL Chrome browser extension, particularly those using versions between v1.22.0 and v1.23.0, should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability has a CVSS score of 5.1 and is classified as medium-severity. It was published on [2026-04-22T05:16:23.253Z] and last modified on [2026-06-16T16:13:00.237Z]. The vulnerability is identified as CWE-79.

Defensive priority

MEDIUM

Recommended defensive actions

  • Update the DeepL Chrome browser extension to a version outside the affected range (v1.22.0 to v1.23.0).
  • Users should ensure they are running the latest version of the extension to mitigate this vulnerability.

Evidence notes

The CVE record and details can be found at [resourceLinkAnnotations:cve-org]. For more information, refer to [resourceLinkAnnotations:nvd]. Additional references include [resourceLinkAnnotations:ref-4] and [resourceLinkAnnotations:ref-5].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-40451 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-40451

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-40451 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-40451

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.