CVE•Published 2026-09-01•Modified 2026-09-03•0 articles on news•4 live references•NVD data

CVE-2026-84642Mozilla · Thunderbird

Vulnerability data via NVD (ingested)

CVSS v3.1

7.5

HIGH

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

EPSS percentile

Exploit Prediction Scoring System · top 96% of all CVEs

Weaknesses (CWE)

CWE-1333Inefficient Regular Expression Complexity

Description

The values of the mail.allowed_attachment_hostnames advanced config setting were used in a regular expression without escaping. For some possible valid hostnames, this could allow certain unintended hostnames to also match and serve remote attachments. This vulnerability was fixed in Thunderbird 155 and Thunderbird 153.2.

Timeline

Published 2026-09-01

Modified 2026-09-03

External references

NVD MITRE Exploit-DB 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-2026-84642

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Mozilla Thunderbird"

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

Shodan · banner/body mention

http.html:"Thunderbird"

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

More intel sources (5)

Shodan report

vuln:CVE-2026-84642