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CVE-2026-78953 Google CVE debrief

A CVE debrief for CVE-2026-78953, a missing authorization vulnerability in SiteIsolation in Google Chrome prior to 152.0.7977.65. This vulnerability allows a remote attacker who has compromised the renderer process to bypass site isolation via a crafted PDF file. Defenders responsible for managing Chrome deployments should assess and prioritize updating Chrome to version 152.0.7977.65 or later. The CVE record and NVD entry provide details on the vulnerability. The vulnerability has a medium severity and was published on 2026-08-25T21:17:51.303Z.

Vendor
Google
Product
Chrome
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-25
Original CVE updated
2026-09-17
Advisory published
2026-08-25
Advisory updated
2026-09-17

Who should care

Defenders responsible for managing Chrome deployments, particularly those with high-risk exposure to PDF files or untrusted sources, should assess and prioritize updating Chrome to version 152.0.7977.65 or later.

Why it matters

CVE-2026-78953 is a missing authorization vulnerability in SiteIsolation in Google Chrome prior to 152.0.7977.65. Defenders should prioritize verifying and applying the Chrome update, assessing exposure for Chrome users, and monitoring for suspicious PDF file activity.

  • Verify and apply Chrome updates to prevent exploitation
  • Assess exposure for Chrome users who opened malicious PDF files
  • Monitor for suspicious PDF file activity

Technical summary

The vulnerability, CVE-2026-78953, is a missing authorization issue in SiteIsolation in Google Chrome prior to 152.0.7977.65. This allows a remote attacker who has compromised the renderer process to bypass site isolation via a crafted PDF file. The vulnerability has a medium severity and defenders should prioritize verifying and applying the Chrome update to version 152.0.7977.65 or later. The CVE record and NVD entry provide details on the vulnerability, but do not specify versions or exploitation details beyond the Chrome update and crafted PDF file.

Defensive priority

Defenders should prioritize verifying and applying the Chrome update to version 152.0.7977.65 or later, and assess exposure for Chrome users who may have opened malicious PDF files.

Recommended defensive actions

  • Verify and apply the Chrome update to version 152.0.7977.65 or later
  • Assess exposure for Chrome users who may have opened malicious PDF files
  • Monitor for suspicious PDF file activity

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but do not specify versions or exploitation details beyond the Chrome update and crafted PDF file.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-78953 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-78953

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

  • CVE-2026-78953 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-78953

    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.