What is the CVSS score of CVE-2026-8949?

CVE-2026-8949 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.0%.

Which versions of Mozilla Firefox are affected by CVE-2026-8949?

Mozilla Firefox for Windows contains a denial-of-service vulnerability (CVE-2026-8949) that crashes the browser when users visit crafted web pages, affecting workforce productivity and requiring…. A patch is available.

How to fix or mitigate CVE-2026-8949?

Within 24 hours: Identify Firefox installations on Windows systems across the organization and prepare user communications. Within 7 days: Deploy Firefox 151 (or Firefox ESR 140.11 for extended-support users) to Windows endpoints via your patch management process, targeting minimum 90% coverage. Within 30 days: Complete full deployment to achieve 100% coverage and validate through compliance scanning.

Mozilla Firefox CVE-2026-8949

EUVD-2026-30899 HIGH

Integer Overflow or Wraparound (CWE-190)

2026-05-19 mozilla

GHSA-wpxg-v53p-m79m

Buffer Overflow Integer Overflow Mozilla

7.5

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

vuln.today AI

6.5 MEDIUM

Network-delivered web content with low complexity and no privileges, but a victim must load attacker content so UI:R; impact is a crash so A:H with C:N/I:N.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SUSE

HIGH

qualitative

Red Hat

6.1 MEDIUM

qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

Jul 23, 2026 - 17:48 vuln.today

CVE Published

May 19, 2026 - 12:29 nvd

UNKNOWN (no severity yet)

CVE Published

May 19, 2026 - 12:29 cve.org

HIGH 7.5

DescriptionCVE.org

Integer overflow in the Widget: Win32 component. This vulnerability was fixed in Firefox 151 and Firefox ESR 140.11.

AnalysisAI

Denial of service in Mozilla Firefox (fixed in Firefox 151 and Firefox ESR 140.11) arises from an integer overflow (CWE-190) in the Windows-specific 'Widget: Win32' component, allowing remote attackers to crash the browser or corrupt memory state via crafted web content. The CVSS 3.1 vector scores availability-only impact (C:N/I:N/A:H), indicating a reliability/crash issue rather than confirmed code execution. There is no public exploit identified at time of analysis, and EPSS is very low (0.04%, 14th percentile).

Technical ContextAI

The flaw is an integer overflow (CWE-190) in Firefox's 'Widget: Win32' subsystem, which is the platform layer responsible for native window management, rendering surfaces, and input/event handling on Microsoft Windows. Integer overflows in such code typically occur when size or offset arithmetic (e.g., computing buffer dimensions for a widget/graphics surface) wraps around a fixed-width integer, yielding an undersized allocation or out-of-bounds index. The CPE (cpe:2.3:a:mozilla:firefox) confirms the affected product is the Firefox application; because the component is Win32-specific, the exposure is inherently limited to Windows builds, even though the CPE string itself is platform-agnostic. Vendor tags additionally flag this as a 'Buffer Overflow / Integer Overflow' class issue, consistent with a memory-safety fault triggered through the native widget path.

RemediationAI

Vendor-released patch: upgrade to Firefox 151 or later, or Firefox ESR 140.11 or later, per the Mozilla advisories (https://www.mozilla.org/security/advisories/mfsa2026-46/ and mfsa2026-48/50/51). On enterprise Linux, apply the distribution updates such as SUSE-SU-2026:2039 (https://www.suse.com/support/update/SUSE-SU-2026:2039/) and the corresponding Red Hat erratum. Because the affected code is the Windows Win32 widget layer, non-Windows deployments are effectively out of scope but should still be updated for consistency. If immediate patching is not possible on Windows endpoints, compensating controls are limited for a browser content bug: reduce exposure by restricting browsing to trusted sites via web proxy/URL filtering and enforcing Firefox auto-update through enterprise policy; note these controls reduce but do not eliminate risk, since any rendered attacker content could trigger the crash. The realistic impact is denial of service, so prioritization can be routine rather than emergency.

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Vendor StatusVendor

SUSE

Severity: High

Product	Status
SUSE Linux Enterprise Server 12 SP5-LTSS	Fixed
SUSE Linux Enterprise Server LTSS Extended Security 12 SP5	Fixed
openSUSE Tumbleweed	Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS	Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS	Affected

CVE-2026-8949 vulnerability details – vuln.today

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Mozilla Firefox CVE-2026-8949

Severity by source

CVSS VectorNVD

Lifecycle Timeline

DescriptionCVE.org

AnalysisAI

Technical ContextAI

RemediationAI

More in Mozilla

Same weakness CWE-190 – Integer Overflow or Wraparound

Same technique Buffer Overflow

Vendor StatusVendor

SUSE

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External POC / Exploit Code