CVE-2026-52687

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{"bugzilla": {"description": "dovecot: dovecot: Denial of Service via IMAP compression memory exhaustion", "id": "2525579", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2525579"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-770", "details": ["An attacker that has valid credentials can select a compression algorithm for the IMAP connection whose decompression state requires a large amount of memory, and open several such connections. The memory limit of the process is reached with only a few connections, terminating the process and all connections it handles, which can cause degradation or denial of service for IMAP. Disable IMAP compression. Alternatively limit the number of connections handled by a single imap-login process, though this has a performance impact. Update to non-vulnerable version. No publicly available exploits are known.", "A flaw was found in dovecot. A remote attacker with valid credentials can exploit this vulnerability by selecting a compression algorithm for the IMAP connection that requires a large amount of memory for decompression. By opening several such connections, the attacker can exhaust the process's memory limit, leading to the termination of the process and all its connections. This can cause degradation or a complete denial of service for IMAP."], "mitigation": {"lang": "en:us", "value": "To mitigate this vulnerability, disable IMAP compression in the Dovecot configuration. This can be achieved by ensuring that `zlib` or other compression plugins are not loaded for IMAP services. For example, remove `zlib` from the `mail_plugins` setting in `dovecot.conf` or a relevant configuration file. A restart of the Dovecot service is required for the changes to take effect. Disabling compression may result in increased network bandwidth usage for IMAP connections."}, "name": "CVE-2026-52687", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "dovecot", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-28T10:12:31Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-52687\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-52687\nhttps://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.3.11,2.4.5)"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}]}, "product": "ox_dovecot_ce", "vendor": "open-xchange"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[2.3.11,2.3.22.2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[3.0.0,3.0.7)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[3.1.0,3.1.6)"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "OX Dovecot Pro", "source": "cna", "vendor": "Open-Xchange GmbH"}, "product": "ox_dovecot_pro", "vendor": "open-xchange"}], "created": "2026-08-28T13:30:07.009524+00:00", "updated": "2026-09-01T16:00:13.702849+00:00", "vendors": ["open-xchange", "open-xchange$PRODUCT$ox_dovecot_ce", "open-xchange$PRODUCT$ox_dovecot_pro"]}