CVE catalog
CVE-2026-63435
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#m
- Severity
- Medium · CVSS 5.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N - Published
- Updated
- Source
- [NVD] · [CVE record]
- EPSS
- 0.45% · Oct 27, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | ruby-mail | sid | 2.9.1-1 | fixed |
| Debian | ruby-mail | forky | 2.9.1-1 | fixed |
| Debian | ruby-mail | trixie | 2.8.1+dfsg1-2 | vulnerable |
| Debian | ruby-mail | bookworm | 2.7.1+dfsg1-2 | vulnerable |
| Rubygems | Not reported | 2.9.1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | ruby-mail | source | sid | 2.9.1-1 | not yet assigned | Not reported | Not reported |
| Debian | ruby-mail | source | forky | 2.9.1-1 | not yet assigned | Not reported | Not reported |
| Debian | ruby-mail | source | trixie | (unfixed) | not yet assigned | Not reported | Not reported |
| Debian | ruby-mail | source | bookworm | (unfixed) | not yet assigned | Not reported | Not reported |
| Rubygems | rubygems | Not reported | 2.9.1 | Not reported | GHSA-MVXR-6M87-MV2Q | Not reported |
Notes
[trixie] ruby-mail: Minor issue [bookworm] ruby-mail: Minor issue
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [ruby-mail]Affected
Details (2)
2.7.1+dfsg1-2· all · bookwormAffected
nvd · ruby-mail · debian · bookworm; nvd · ruby-mail · debian · 12
2.7.1+dfsg1-2· all · bookwormAffected
nvd · ruby-mail · debian · bookworm; nvd · ruby-mail · debian · 12
[Debian 13 (Trixie)]
- [ruby-mail]Affected
Details (2)
2.8.1+dfsg1-2· all · trixieAffected
nvd · ruby-mail · debian · 13
2.8.1+dfsg1-2· all · trixieAffected
nvd · ruby-mail · debian · 13
Observed:
References
- [https://github.com/advisories/GHSA-mvxr-6m87-mv2q]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-63435]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-63435]
- [https://security-tracker.debian.org/tracker/CVE-2026-63435]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63435.json]
[Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]