What is the CVSS score of CVE-2026-8388?

CVE-2026-8388 has a CVSS 3.1 base score of 6.5 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Is there a patch available for CVE-2026-8388?

Yes, a patch is available for CVE-2026-8388. Update the affected software to the latest version immediately.

Mozilla Firefox CVE-2026-8388

EUVD-2026-29462 MEDIUM

Buffer Overflow (CWE-119)

2026-05-12 mozilla

GHSA-6cv4-3h2g-632h

Buffer Overflow Mozilla

6.5

CVSS 3.1 · Vendor: mozilla

Severity by source

Vendor (mozilla) PRIMARY

6.5 MEDIUM

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

vuln.today AI

5.4 MEDIUM

Browser JIT exploitation requires user navigation to attacker content, making UI:R more accurate than the provided UI:N; all other metrics retained from vendor data.

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

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

SUSE

MEDIUM

qualitative

Red Hat

7.5 HIGH

qualitative

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Jul 23, 2026 - 22:29 vuln.today

CVSS changed

May 12, 2026 - 19:22 NVD

6.5 (MEDIUM)

CVE Published

May 12, 2026 - 12:36 nvd

MEDIUM 6.5

CVE Published

May 12, 2026 - 12:36 nvd

UNKNOWN (no severity yet)

DescriptionCVE.org

Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 150.0.3.

AnalysisAI

Incorrect boundary conditions in Firefox's JavaScript JIT compiler expose network-reachable memory corruption in all Firefox versions prior to 150.0.3, yielding partial confidentiality and integrity impact per CVSS C:L/I:L. The flaw is classified under CWE-119 (buffer bounds violation) and carries a CVSS 6.5 Medium score with an AV:N/AC:L/PR:N/UI:N vector - though the UI:N designation warrants scrutiny for a browser-based JIT flaw (see confidence notes). SSVC assesses technical impact as partial with no confirmed exploitation, and EPSS places exploitation probability at 0.03% (8th percentile), indicating low real-world exploitation pressure despite the network-reachable vector. No public exploit identified at time of analysis.

Technical ContextAI

The vulnerability resides in Firefox's JavaScript engine JIT (Just-In-Time) compilation subsystem, identified via CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*. JIT compilers transform bytecode into native machine code at runtime to accelerate JavaScript execution; CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) indicates that incorrect boundary conditions allow reads or writes beyond allocated memory regions during this compilation or execution phase. Such flaws in JIT engines can permit an attacker-controlled JavaScript payload to corrupt adjacent memory, potentially leaking heap or stack data (C:L) or overwriting values in adjacent structures (I:L). The absence of A impact (A:N) suggests this does not cause crashes or denial of service reliably. Multiple Linux distribution vendors (SUSE via SUSE-SU-2026:2039 and Red Hat via multiple RHSA errata) have issued updated Firefox packages, confirming broad upstream patch propagation.

RemediationAI

Upgrade Mozilla Firefox to version 150.0.3 or later, which contains the vendor-confirmed fix for this boundary condition error in the JIT engine. The authoritative patch advisory is Mozilla Security Advisory mfsa2026-45 at https://www.mozilla.org/security/advisories/mfsa2026-45/. Red Hat Enterprise Linux users should apply the relevant RHSA errata (e.g., RHSA-2026:21378 through RHSA-2026:26174) via standard package management; SUSE Linux Enterprise users should apply SUSE-SU-2026:2039. For environments where immediate upgrade is not feasible, consider disabling JIT compilation via the Firefox preference javascript.options.ion and javascript.options.baselinejit set to false in about:config - this eliminates the vulnerable code path at the cost of significant JavaScript execution performance degradation (typically 20-50% slowdown on JS-heavy workloads). Enterprise deployments can enforce this via Group Policy or Firefox policies.json. Blocking untrusted or unknown web content via proxy filtering provides additional defense-in-depth but is not a substitute for patching.

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Vendor StatusVendor

SUSE

Severity: Medium

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-2026-8388 vulnerability details – vuln.today

Back

Mozilla Firefox CVE-2026-8388

Severity by source

CVSS VectorVendor: mozilla

Lifecycle Timeline

DescriptionCVE.org

AnalysisAI

Technical ContextAI

RemediationAI

More in Mozilla

Same weakness CWE-119 – Buffer Overflow

Same technique Buffer Overflow

Vendor StatusVendor

SUSE

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External POC / Exploit Code