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)
ReferencesDLA-4766-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
cyrus-imapd (PTS)bookworm3.6.1-4+deb12u4vulnerable
bookworm (security)3.6.1-4+deb12u5fixed
trixie3.10.2-1+deb13u2fixed
forky, sid3.12.4-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
cyrus-imapdsourcebookworm3.6.1-4+deb12u5DLA-4766-1
cyrus-imapdsourcetrixie3.10.2-1+deb13u2
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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