CVE•Published 2026-05-12•Modified 2026-07-15•0 articles on news•5 live references•NVD data

CVE-2026-8391Mozilla · Firefox

Vulnerability data via NVD (ingested)

CVSS v3.1

5.3

MEDIUM

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

EPSS percentile

Exploit Prediction Scoring System · top 78% of all CVEs

Weaknesses (CWE)

CWE-20Improper Input Validation CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer CWE-475Undefined Behavior for Input to API

Description

Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.

Timeline

Published 2026-05-12

Modified 2026-07-15

External references

NVD MITRE Exploit-DB GitHub PoC VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-8391

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Mozilla Firefox"

All exposed Mozilla Firefox instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Firefox"

HTTP body or banner mentions "Firefox" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-8391