CVE-2026-63435

NameCVE-2026-63435
DescriptionMail 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
ruby-mail (PTS)bookworm2.7.1+dfsg1-2vulnerable
trixie2.8.1+dfsg1-2vulnerable
forky, sid2.9.1-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
ruby-mailsource(unstable)2.9.1-1

Notes

[trixie] - ruby-mail <no-dsa> (Minor issue)
https://github.com/mikel/mail/security/advisories/GHSA-mvxr-6m87-mv2q
https://github.com/mikel/mail/pull/1664
Fixed by: https://github.com/mikel/mail/commit/f9d59c2e447af42e2c3dec5a56b1bb25c7292859 (2.9.1)

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