CVE-2025-14330Public exploit

JavaScript crash via incorrect RISC-V tag extraction

Published Dec 9, 2025 · Updated Apr 13, 2026

JIT miscompilation in Firefox, Firefox ESR, and Thunderbird allows attackers to crash RISC-V JavaScript execution via crafted JavaScript. The unboxGCThingForGCBarrier routine passes JSVAL_TAG_SHIFT minus one to ExtractBits, producing an invalid pointer in the pre-barrier path. The demonstrated trigger runs in the RISC-V simulator's JavaScript shell, and Mozilla marks the issue as limited to a tier 3 platform.

CVSS severity9.8
Critical
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

JIT miscompilation in Firefox, Firefox ESR, and Thunderbird allows attackers to crash RISC-V JavaScript execution via crafted JavaScript. The unboxGCThingForGCBarrier routine passes JSVAL_TAG_SHIFT minus one to ExtractBits, producing an invalid pointer in the pre-barrier path. The demonstrated trigger runs in the RISC-V simulator's JavaScript shell, and Mozilla marks the issue as limited to a tier 3 platform.

The record

CVE
CVE-2025-14330
Published
Dec 9, 2025
Updated
Apr 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-119, CWE-843, CWE-686
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.1SUSECVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1Oracle LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.1SUSECVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
CWE-686Function Call With Incorrect Argument Type

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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