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PatchSiren cyber security CVE debrief

CVE-2026-45243 steipete CVE debrief

A missing authorization vulnerability in the Summarize browser extension (versions prior to 0.15.1) allows malicious web pages to perform unauthorized operations on automation artifacts. The flaw exists in the content script window.postMessage bridge, which fails to properly validate message sender identifiers. Attackers can spoof runtime messages to list, read, create, overwrite, or delete automation artifacts scoped to the affected tab without authorization checks. The vulnerability was disclosed on 2026-05-18 and carries a CVSS 4.0 score of 5.3 (Medium severity). A patch is available in version 0.15.1, with release notes published for v0.15.2.

Vendor
steipete
Product
summarize
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-18
Original CVE updated
2026-10-08
Advisory published
2026-05-18
Advisory updated
2026-10-08

Who should care

Organizations and individuals using the Summarize browser extension for web automation tasks, security teams managing browser extension deployments, and developers building browser extensions with cross-origin messaging capabilities.

Technical summary

The Summarize browser extension's content script implements a window.postMessage bridge for cross-origin communication with the extension's background context. The bridge fails to implement proper authorization checks on incoming messages, allowing any web page to spoof sender identifiers and issue runtime messages. This enables attackers to perform CRUD operations (create, read, update, delete) on automation artifacts that should be scoped and protected per-tab. The vulnerability is classified as CWE-862 (Missing Authorization) and affects all versions before 0.15.1. The fix implements proper sender validation and authorization checks in the postMessage handler.

Defensive priority

medium

Recommended defensive actions

  • Update Summarize browser extension to version 0.15.1 or later
  • Review browser extension permissions and remove untrusted extensions
  • Monitor for unauthorized automation artifact modifications in affected browser profiles
  • Apply principle of least privilege for browser extension installations

Evidence notes

Vulnerability identified in content script postMessage bridge; missing authorization checks on sender validation. CWE-862 (Missing Authorization). Affected versions: all versions prior to 0.15.1.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-45243 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-45243

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

  • CVE-2026-45243 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45243

    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.