Security readout for executives and security teams
Plain-English summary
CVE-2026-27856 affects doveadm credential checking in OX Dovecot Pro. Because credentials are compared directly, a remote attacker may be able to infer the configured credential through timing differences. Successful recovery could give full access to the affected component.
Executive priority
Treat this as a high-priority administrative-service exposure issue. Prioritize externally reachable or broadly reachable doveadm HTTP services first, because credential recovery could lead to full component access even though public exploit evidence is not reported.
Technical view
The issue is a timing oracle in doveadm HTTP credential verification, mapped to CWE-208 and CWE-287. CVSS 3.1 is 7.4 high: network reachable, unauthenticated, high attack complexity, no user interaction, with high confidentiality and integrity impact.
Likely exposure
Exposure is most likely where the doveadm HTTP service port is enabled and reachable by untrusted networks. The source bundle names OX Dovecot Pro, but exact affected version detail is sparse and should be validated against vendor CSAF and Red Hat advisories.
Exploitation context
The provided record says no publicly available exploits are known. CISA KEV status is false, so active exploitation should not be assumed from these sources. Exploitation appears constrained by high complexity, but the impact is serious if credentials are recovered.
Researcher notes
Evidence supports a timing side-channel in direct credential comparison, not a broadly weaponized exploit. The affected-version data in the bundle is limited, including an ambiguous version value, so researchers should rely on vendor CSAF and Red Hat errata for exact applicability.
Mitigation direction
- Limit access to the doveadm HTTP service port to trusted administrative networks.
- Install the fixed vendor version when applicable to your deployment.
- Review Open-Xchange and Red Hat advisories for exact package applicability.
- Disable unnecessary doveadm HTTP exposure if operationally feasible.
- Monitor authentication and administrative access logs for unusual activity.
Validation and detection
- Inventory OX Dovecot Pro and Red Hat-packaged Dovecot deployments.
- Confirm whether the doveadm HTTP service is enabled.
- Check whether the doveadm HTTP port is reachable from untrusted networks.
- Compare installed versions against vendor CSAF and Red Hat errata.
- Verify firewall or access-control restrictions around administrative service ports.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-208: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-287: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-27856 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N2.25.2OXCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N2.25.2redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
7.4HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Base CVSS 3.1 score
7.4HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-03-27T09:01:28.297Z: Reported to Red Hat.
- 2026-03-27T08:10:19.537Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.jsonCVE reference, OX · vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-27856CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2452171CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27856.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:26564CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Observable Timing Discrepancy
Observable Timing Discrepancy represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Improper Authentication
Improper Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.