CVE-2026-91738: Chromium CVE-2026-91738: Improper input validation
CVE-2026-91738 is a vulnerability in Chromium CVE-2026-91738: Improper input validation, rated Moderate by Microsoft, with a CVSS 3.1 base score of 9.6 (Critical). An attacker can exploit it remotely over the network, without any privileges and only if a user takes an action. Microsoft has not reported exploitation in the wild. The EPSS model estimates a 0.33% probability of exploitation activity in the next 30 days, higher than 26% of all scored vulnerabilities. Microsoft released the fix on 17 September 2026, outside Patch Tuesday. It affects 2 products in 1 product family (Browser).
Key facts
- CVE ID
- CVE-2026-91738
- Severity
- Critical CVSS 9.6
- Microsoft severity
- Moderate
- Exploited in the wild
- No
- Publicly disclosed
- No
- Weakness
- CWE-20
- EPSS
- 0.33% (percentile 26%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- September 2026 Patch Tuesday
- Product families
- Browser
CVSS score and vector
Microsoft scores CVE-2026-91738 at 9.6 (temporal 9.6) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | Required |
| Scope | Changed |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | High |
Description
This CVE was assigned by Chrome. Microsoft Edge (Chromium-based) ingests Chromium, which addresses this vulnerability. Please see Google Chrome Releases](https://chromereleases.googleblog.com/2026)) for more information.
Frequently asked questions (Microsoft)
Why is this Chrome CVE included in the Security Update Guide?
The vulnerability assigned to this CVE is in Chromium Open Source Software (OSS) which is consumed by Microsoft Edge (Chromium-based). It is being documented in the Security Update Guide to announce that the latest version of Microsoft Edge (Chromium-based) is no longer vulnerable.
How can I see the version of the browser?
- In your Microsoft Edge browser, click on the 3 dots (...) on the very right-hand side of the window
- Click on Help and Feedback
- Click on About Microsoft Edge
Affected products (2)
Browser
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Microsoft Edge (Chromium-based) | Release Notes | Security Update | 153.0.4234.46 | No |
| Microsoft Edge (Chromium-based) | Release Notes | Security Update | 153.0.4234.46 | No |
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 9.6 (CRITICAL)
- NVD weakness
- CWE-20
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| chrome | before 153.0.8010.47 |
References
- https://chromereleases.googleblog.com/2026/09/stable-channel-update-for-desktop_0541751186.html (Release Notes, Vendor Advisory)
- https://issues.chromium.org/issues/536450979 (Permissions Required)
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. | |
| 2.0 | Information published. |