CVE-2018-18509 Security feature bypass in Thunderbird

What is CVE-2018-18509?

CVE-2018-18509 is a medium-severity vulnerability in Mozilla Thunderbird, published on 26 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A flaw during verification of certain S/MIME signatures causes emails to be shown in Thunderbird as having a valid digital signature, even if the shown message contents aren't covered by the signature. The flaw allows an attacker to reuse a valid S/MIME signature to craft an email message with arbitrary content. This vulnerability affects Thunderbird < 60.5.1.

Weakness: CWE-347

Which versions are affected by CVE-2018-18509?

It affects 1 product.

Products include Mozilla Thunderbird.

How do I fix CVE-2018-18509?

Upgrade to a fixed version.

Is CVE-2018-18509 being exploited?

There is no known exploitation of CVE-2018-18509 in the wild and no public exploit code.

Other vulnerabilities in Mozilla Thunderbird

• CVE-2026-92238 Ambiguous parsing of mail headers Critical 9.8
• CVE-2026-84637 Calendar invitation attachments could launch local executables Critical 9.8
• CVE-2021-43529 Memory corruption in Thunderbird Critical 9.8
• CVE-2019-11703 Memory corruption in Thunderbird Critical 9.8
• CVE-2019-11704 Memory corruption in Thunderbird Critical 9.8

All Mozilla Thunderbird vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2018-18509, GHSA-pqr9-248w-h9pf, UBUNTU-CVE-2018-18509.