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{"bugzilla": {"description": "NGINX: NGINX: Denial of Service via undisclosed requests when ngx_mail_auth_http_module is enabled", "id": "2450791", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450791"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-476", "details": ["A flaw was found in NGINX, specifically within the ngx_mail_auth_http_module. When this module is enabled, and CRAM-MD5 or APOP authentication is active with an authentication server that permits retries, undisclosed requests can cause NGINX worker processes to terminate. This can lead to a Denial of Service (DoS), making the affected NGINX instance unavailable to legitimate users."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2026-27651", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "nginx", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "nginx:1.24/nginx", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "nginx", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "nginx:1.24/nginx", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "nginx:1.26/nginx", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-03-24T14:13:27Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-27651\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-27651\nhttps://my.f5.com/manage/s/article/K000160383"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[1.29.0,1.29.7)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0.5.15,1.28.3)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "NGINX Open Source", "source": "cna", "vendor": "F5"}, "product": "nginx_open_source", "vendor": "f5"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[R36,R36 P3)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[R35,R35 P2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[R34,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[R33,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[R32,R32 P5)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "NGINX Plus", "source": "cna", "vendor": "F5"}, "product": "nginx_plus", "vendor": "f5"}], "analysis": {"en": {"generated_at": "2026-03-24T15:20:39.396768+00:00", "value": {"mitigation_remediation": ["Apply the latest vendor patch or update to a recent, supported version of NGINX.", "If upgrading is not immediately possible, disable the ngx_mail_auth_http_module in the NGINX configuration.", "Restrict or disable the use of the Auth\u2011Wait response header in the authentication server to eliminate retry behavior.", "Monitor server logs for unexpected worker crashes and review authentication traffic for anomalous requests."], "summary": {"action": "Immediate Patch", "impact": "Denial of Service via worker process crash"}, "threat_synthesis": {"affected_systems": "Affecting F5:NGINX Open Source and F5:NGINX Plus. No specific version information is provided, so all supported versions of these products should be considered at risk until a vendor confirmation or patch is released.", "description_and_impact": "Enabling the ngx_mail_auth_http_module in NGINX Open Source or NGINX Plus introduces a flaw that can terminate worker processes when undetermined requests are received. The vulnerability stems from a NULL pointer scenario represented by CWE\u2011476, allowing an attacker to cause a denial of service by provoking the worker process to crash. The impact is strictly on availability, potentially resulting in service interruption for the affected server.", "risk_and_exploitability": "The CVSS score of 8.7 classifies the issue as high severity. Exploitability details such as EPSS are unavailable, and the vulnerability is not listed in the CISA KEV catalog. The attack vector is inferred to be remote, leveraging the mail authentication protocols CRAM\u2011MD5 or APOP. An adversary could send crafted authentication requests with an Auth\u2011Wait header from the authentication server, triggering the worker process crash."}}}}, "created": "2026-03-25T11:47:22.465646+00:00", "updated": "2026-03-25T20:50:07.953150+00:00", "vendors": ["f5", "f5$PRODUCT$nginx_open_source", "f5$PRODUCT$nginx_plus"]}