RLSA-2026:76763 (CVE-2026-27852)

Vulnerability from osv_rocky – Published: 2026-10-07 06:01 – Updated: 2026-10-07 12:14 – Source website
VLAI
Summary
Important: dovecot security, bug fix, and enhancement update
Details

Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind. It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL drivers and authentication plug-ins are provided as subpackages.

Security Fix(es):

  • dovecot: Dovecot: Denial of Service via IMAP ID command with excessive parameters (CVE-2026-42391)

  • dovecot: Dovecot: Authentication bypass via incorrect OAuth2 token validation (CVE-2026-73208)

  • dovecot: Dovecot: Denial of service via crafted email headers (CVE-2026-27852)

  • dovecot: Dovecot: Denial of Service via truncated quoted argument in ManageSieve (CVE-2026-40019)

  • dovecot: Dovecot: Denial of Service and potential message duplication via connection limit exhaustion (CVE-2026-33263)

  • dovecot: Dovecot: Denial of Service in ManageSieve login process (CVE-2026-33605)

  • dovecot: Dovecot: Arbitrary Code Execution via Sieve editheader use-after-free (CVE-2026-42007)

  • dovecot: Dovecot: MySQL multi-byte escaping wrong (CVE-2026-40018)

Bug Fix(es) and Enhancement(s):

  • Dovecot crashes when accessing mailbox with: "Panic: file mail-user.c: line 229 (mail_user_deinit): assertion failed: ((*user)->refcount == 1)" (JIRA:Rocky Linux-176273)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H
Credits
Rocky Enterprise Software Foundation
Red Hat
References
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Rocky Linux:8",
        "name": "dovecot",
        "purl": "pkg:rpm/rocky-linux/dovecot?distro=rocky-linux-8\u0026epoch=1"
      },
      "ranges": [
        {
          "database_specific": {
            "yum_repository": "AppStream"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.3.16-16.el8_10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "credits": [
    {
      "name": "Rocky Enterprise Software Foundation"
    },
    {
      "name": "Red Hat"
    }
  ],
  "database_specific": {
    "license": "CC-BY-4.0",
    "license_url": "https://creativecommons.org/licenses/by/4.0/",
    "source_advisory": "RHSA-2026:76763"
  },
  "details": "Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind. It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL drivers and authentication plug-ins are provided as subpackages. \n\nSecurity Fix(es):\n\n* dovecot: Dovecot: Denial of Service via IMAP ID command with excessive parameters (CVE-2026-42391)\n\n* dovecot: Dovecot: Authentication bypass via incorrect OAuth2 token validation (CVE-2026-73208)\n\n* dovecot: Dovecot: Denial of service via crafted email headers (CVE-2026-27852)\n\n* dovecot: Dovecot: Denial of Service via truncated quoted argument in ManageSieve (CVE-2026-40019)\n\n* dovecot: Dovecot: Denial of Service and potential message duplication via connection limit exhaustion (CVE-2026-33263)\n\n* dovecot: Dovecot: Denial of Service in ManageSieve login process (CVE-2026-33605)\n\n* dovecot: Dovecot: Arbitrary Code Execution via Sieve editheader use-after-free (CVE-2026-42007)\n\n* dovecot: Dovecot: MySQL multi-byte escaping wrong (CVE-2026-40018)\n\nBug Fix(es) and Enhancement(s):\n\n* Dovecot crashes when accessing mailbox with: \"Panic: file mail-user.c: line 229 (mail_user_deinit): assertion failed: ((*user)-\u003erefcount == 1)\" (JIRA:Rocky Linux-176273)\n\nFor more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.",
  "id": "RLSA-2026:76763",
  "modified": "2026-10-07T12:14:49.797299Z",
  "published": "2026-10-07T06:01:37.070463Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://errata.rockylinux.org/RLSA-2026:76763"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525545"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525547"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525557"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525559"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525567"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525576"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525583"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525584"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:76763"
    }
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Important: dovecot security, bug fix, and enhancement update",
  "upstream": [
    "CVE-2026-27852",
    "CVE-2026-33263",
    "CVE-2026-33605",
    "CVE-2026-40018",
    "CVE-2026-40019",
    "CVE-2026-42007",
    "CVE-2026-42391",
    "CVE-2026-73208"
  ]
}



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