CVE-2026-47085

NameCVE-2026-47085
DescriptionAn issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. URLAUTH token forgery can occur via a missing mboxkey. If an attacker knew a folder name on the victim's account for which the victim had never issued an auth URL, they could forge a working URLAUTH token by computing an HMAC-SHA1 value with a predictable key, giving them read access to the mailbox. (URLAUTH is an obscure feature, meaning that the odds of any user actually being susceptible to this attack are very low. Perhaps no public clients use URLAUTH.)
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
cyrus-imapd (PTS)bullseye3.2.6-2+deb11u2vulnerable
bullseye (security)3.2.6-2+deb11u4vulnerable
bookworm3.6.1-4+deb12u4vulnerable
bookworm (security)3.6.1-4+deb12u2vulnerable
trixie3.10.2-1vulnerable
forky3.12.2-1vulnerable
sid3.12.3-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
cyrus-imapdsource(unstable)3.12.3-1

Notes

https://www.cyrusimap.org/3.12/imap/download/release-notes/3.12/x/3.12.3.html

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