Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.30% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-47085High confidence
cyrusimap Cyrus IMAP — Generation of Predictable Numbers or Identifiers
cyrusimap · Cyrus IMAP
4.0MediumCVSS 3.1
Scheduled
Fix not verifiedMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs cyrusimap Cyrus IMAP and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | cyrus-imapd | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.10.2-1+deb13u2 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian bookwormbookworm · source | cyrus-imapd | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.6.1-4+deb12u5 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian forkyforky · source | cyrus-imapd | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.12.3-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian sidsid · source | cyrus-imapd | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.12.3-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · esm-apps | cyrus-imapd | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Fix not verified01
What, why and how
An 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.)
What
An 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.)
Why
The product uses a scheme that generates numbers or identifiers that are more predictable than required.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
An 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.)
Why
The product uses a scheme that generates numbers or identifiers that are more predictable than required.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Generation of Predictable Numbers or Identifiers → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- High: exploitation depends on specific conditions
- Security boundary
- Changed: exploitation can affect a different security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-340 ↗
CWE-340: Generation of Predictable Numbers or Identifiers. The product uses a scheme that generates numbers or identifiers that are more predictable than required.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:NCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security authority.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix not verified
- Affected
- Cyrus IMAP: < 3.12.3
- Fixed
- No fixed version is explicitly recorded in the structured CVE data.
- Action
- No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 16 Jul 2026 · Last source change 16 Jul 2026, 18:54 UTC · CWE-340 · Generation of Predictable Numbers or Identifiers
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-45008
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.