CVE-2026-63435
mediumMail is an internet library for Ruby designed to handle email generation, parsing, and sending.
Mail is an internet library for Ruby designed to handle email generation, parsing, and sending. Prior to 2.9.1, Mail::Utilities.q_value_decode and Mail::Utilities.b_value_decode used a single String#match and an overly greedy charset capture to decode only the first RFC 2047 encoded-word and mishandle surrounding or subsequent text. A crafted malformed encoded-word in an address display name or local part could cross ? delimiters and make decoded From, To, or Reply-To header values differ from the raw values inspected by a human reviewer or downstream parser, enabling apparent sender or recipient spoofing, phishing, or authorization-check bypass. This issue is fixed in version 2.9.1.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/mikel/mail/commit/f9d59c2e447af42e2c3dec5a56b1bb25c7292859 security-advisories@github.com
- https://github.com/mikel/mail/pull/1664 security-advisories@github.com
- https://github.com/mikel/mail/releases/tag/2.9.1 security-advisories@github.com
- https://github.com/mikel/mail/security/advisories/GHSA-mvxr-6m87-mv2q security-advisories@github.com