Security readout for executives and security teams
Plain-English summary
A memory-safety flaw in Chrome’s Chromecast component could let an attacker escape the browser sandbox and take control of the browser process. Exploitation requires a crafted web page and an already-compromised renderer, so this is a chained attack rather than a standalone initial compromise.
Executive priority
Treat as an urgent browser update because successful exploitation could cross Chrome’s sandbox and affect confidentiality, integrity, and availability. Accelerate deployment, but avoid claiming an active campaign: the supplied evidence confirms severity and technical impact, not exploitation in the wild.
Technical view
CVE-2026-78939 is a use-after-free vulnerability (CWE-416) in Chrome’s Chromecast component before version 152.0.7977.65. A remote attacker controlling a renderer process could use crafted HTML to execute arbitrary code outside the sandbox. The supplied CVSS 3.1 score is 9.6, while Chromium classifies the issue as High severity.
Likely exposure
Chrome installations older than 152.0.7977.65 are potentially exposed. Practical risk is greatest where users browse untrusted content and another vulnerability or technique can first compromise the renderer process. The supplied evidence does not identify other affected Chromium-based products.
Exploitation context
The supplied sources do not report active exploitation, and the CVE is not listed as KEV in the bundle. Successful exploitation requires user interaction with crafted HTML and prior renderer compromise. Public exploit availability and attack-chain details are not established by the provided evidence.
Researcher notes
The vulnerability is a Chromecast use-after-free with a renderer-to-browser sandbox-escape impact. Its prerequisite renderer compromise materially affects standalone exploitability, although it could be valuable in a vulnerability chain. The supplied bundle provides no root-cause detail, proof of concept, affected platform breakdown, or evidence of exploitation.
Mitigation direction
- Update Google Chrome to version 152.0.7977.65 or later.
- Prioritize systems used for untrusted browsing or handling sensitive information.
- Consult Google’s release guidance for platform-specific rollout details.
- Use browser-management controls to prevent unsupported or outdated Chrome versions.
Validation and detection
- Inventory installed Chrome versions and identify releases older than 152.0.7977.65.
- Confirm managed endpoints completed the update and restarted Chrome.
- Re-scan endpoints after deployment to verify the vulnerable version is absent.
- Review security telemetry for renderer compromises or unusual sandbox-escape indicators.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-78939 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H2.86CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.6CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://chromereleases.googleblog.com/2026/08/stable-channel-update-for-desktop_0256176589.htmlCVE reference, Chrome
- https://issues.chromium.org/issues/513261751CVE reference, Chrome
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.