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OESA-2026-2722 (CVE-2026-33603)

Vulnerability from osv_openeuler – Published: 2026-06-24 11:11 – Updated: 2026-08-06 11:11 – Source website
VLAI
Summary
dovecot security update
Details

Dovecot is an IMAP server for Linux/UNIX-like systems, written with security primarily in mind. It also contains a small POP3 server. It supports mail in either of maildir or mbox formats.

Security Fix(es):

Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known.(CVE-2026-33603)

Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. No publicly available exploits are known.(CVE-2026-40016)

Attacker can use the IMAP SETACL command to inject the anyone permission to user's dovecot-acl file even if imap_acl_allow_anyone=no. This causes folders to be spammed to all users. The impact is limited to being able to spam folders to other users, no unexpected access is gained. Install to fixed version. No publicly available exploits are known.(CVE-2026-40020)

An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.(CVE-2026-42006)

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "aarch64": [
          "dovecot-2.3.20-5.oe2403sp3.aarch64.rpm",
          "dovecot-debuginfo-2.3.20-5.oe2403sp3.aarch64.rpm",
          "dovecot-debugsource-2.3.20-5.oe2403sp3.aarch64.rpm",
          "dovecot-devel-2.3.20-5.oe2403sp3.aarch64.rpm",
          "dovecot-help-2.3.20-5.oe2403sp3.aarch64.rpm"
        ],
        "src": [
          "dovecot-2.3.20-5.oe2403sp3.src.rpm"
        ],
        "x86_64": [
          "dovecot-2.3.20-5.oe2403sp3.x86_64.rpm",
          "dovecot-debuginfo-2.3.20-5.oe2403sp3.x86_64.rpm",
          "dovecot-debugsource-2.3.20-5.oe2403sp3.x86_64.rpm",
          "dovecot-devel-2.3.20-5.oe2403sp3.x86_64.rpm",
          "dovecot-help-2.3.20-5.oe2403sp3.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP3",
        "name": "dovecot",
        "purl": "pkg:rpm/openEuler/dovecot\u0026distro=openEuler-24.03-LTS-SP3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.20-5.oe2403sp3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "dovecot-2.3.15-8.oe2003sp4.aarch64.rpm",
          "dovecot-debuginfo-2.3.15-8.oe2003sp4.aarch64.rpm",
          "dovecot-debugsource-2.3.15-8.oe2003sp4.aarch64.rpm",
          "dovecot-devel-2.3.15-8.oe2003sp4.aarch64.rpm",
          "dovecot-help-2.3.15-8.oe2003sp4.aarch64.rpm"
        ],
        "src": [
          "dovecot-2.3.15-8.oe2003sp4.src.rpm"
        ],
        "x86_64": [
          "dovecot-2.3.15-8.oe2003sp4.x86_64.rpm",
          "dovecot-debuginfo-2.3.15-8.oe2003sp4.x86_64.rpm",
          "dovecot-debugsource-2.3.15-8.oe2003sp4.x86_64.rpm",
          "dovecot-devel-2.3.15-8.oe2003sp4.x86_64.rpm",
          "dovecot-help-2.3.15-8.oe2003sp4.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:20.03-LTS-SP4",
        "name": "dovecot",
        "purl": "pkg:rpm/openEuler/dovecot\u0026distro=openEuler-20.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.15-8.oe2003sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "dovecot-2.3.15-8.oe2203sp4.aarch64.rpm",
          "dovecot-debuginfo-2.3.15-8.oe2203sp4.aarch64.rpm",
          "dovecot-debugsource-2.3.15-8.oe2203sp4.aarch64.rpm",
          "dovecot-devel-2.3.15-8.oe2203sp4.aarch64.rpm",
          "dovecot-help-2.3.15-8.oe2203sp4.aarch64.rpm"
        ],
        "src": [
          "dovecot-2.3.15-8.oe2203sp4.src.rpm"
        ],
        "x86_64": [
          "dovecot-2.3.15-8.oe2203sp4.x86_64.rpm",
          "dovecot-debuginfo-2.3.15-8.oe2203sp4.x86_64.rpm",
          "dovecot-debugsource-2.3.15-8.oe2203sp4.x86_64.rpm",
          "dovecot-devel-2.3.15-8.oe2203sp4.x86_64.rpm",
          "dovecot-help-2.3.15-8.oe2203sp4.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:22.03-LTS-SP4",
        "name": "dovecot",
        "purl": "pkg:rpm/openEuler/dovecot\u0026distro=openEuler-22.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.15-8.oe2203sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "dovecot-2.3.20-5.oe2403sp1.aarch64.rpm",
          "dovecot-debuginfo-2.3.20-5.oe2403sp1.aarch64.rpm",
          "dovecot-debugsource-2.3.20-5.oe2403sp1.aarch64.rpm",
          "dovecot-devel-2.3.20-5.oe2403sp1.aarch64.rpm",
          "dovecot-help-2.3.20-5.oe2403sp1.aarch64.rpm"
        ],
        "src": [
          "dovecot-2.3.20-5.oe2403sp1.src.rpm"
        ],
        "x86_64": [
          "dovecot-2.3.20-5.oe2403sp1.x86_64.rpm",
          "dovecot-debuginfo-2.3.20-5.oe2403sp1.x86_64.rpm",
          "dovecot-debugsource-2.3.20-5.oe2403sp1.x86_64.rpm",
          "dovecot-devel-2.3.20-5.oe2403sp1.x86_64.rpm",
          "dovecot-help-2.3.20-5.oe2403sp1.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP1",
        "name": "dovecot",
        "purl": "pkg:rpm/openEuler/dovecot\u0026distro=openEuler-24.03-LTS-SP1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.20-5.oe2403sp1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "Medium"
  },
  "details": "Dovecot is an IMAP server for Linux/UNIX-like systems, written with security  primarily in mind.  It also contains a small POP3 server.  It supports mail  in either of maildir or mbox formats.\r\n\r\nSecurity Fix(es):\n\nAttacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known.(CVE-2026-33603)\n\nAttacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. No publicly available exploits are known.(CVE-2026-40016)\n\nAttacker can use the IMAP SETACL command to inject the anyone permission to user\u0026apos;s dovecot-acl file even if imap_acl_allow_anyone=no. This causes folders to be spammed to all users. The impact is limited to being able to spam folders to other users, no unexpected access is gained. Install to fixed version. No publicly available exploits are known.(CVE-2026-40020)\n\nAn attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.(CVE-2026-42006)",
  "id": "OESA-2026-2722",
  "modified": "2026-08-06T11:11:39Z",
  "published": "2026-06-24T11:11:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2722"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33603"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40016"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40020"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42006"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "dovecot security update",
  "upstream": [
    "CVE-2026-33603",
    "CVE-2026-40016",
    "CVE-2026-40020",
    "CVE-2026-42006"
  ]
}



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