{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-9256", "assignerOrgId": "9dacffd4-cb11-413f-8451-fbbfd4ddc0ab", "state": "PUBLISHED", "assignerShortName": "f5", "dateReserved": "2026-05-21T20:58:58.484Z", "datePublished": "2026-05-22T14:11:41.877Z", "dateUpdated": "2026-08-25T12:05:55.163Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "9dacffd4-cb11-413f-8451-fbbfd4ddc0ab", "shortName": "f5", "dateUpdated": "2026-05-28T18:20:47.449Z" }, "title": "NGINX ngx_http_rewrite_module vulnerability", "datePublic": "2026-05-22T14:00:00.000Z", "problemTypes": [ { "descriptions": [ { "lang": "en", "cweId": "CWE-122", "description": "CWE-122 Heap-based Buffer Overflow", "type": "CWE" } ] } ], "affected": [ { "vendor": "F5", "product": "NGINX Plus", "modules": [ "ngx_http_rewrite_module" ], "versions": [ { "status": "affected", "version": "37.0", "lessThan": "37.0.1.1", "versionType": "custom" }, { "status": "affected", "version": "R36", "lessThan": "R36 P5", "versionType": "custom" }, { "status": "affected", "version": "R32", "lessThan": "R32 P7", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "F5", "product": "NGINX Open Source", "modules": [ "ngx_http_rewrite_module" ], "versions": [ { "status": "affected", "version": "1.31.0", "lessThan": "1.31.1", "versionType": "custom" }, { "status": "affected", "version": "1.30.0", "lessThan": "1.30.2", "versionType": "custom" }, { "status": "affected", "version": "0.1.17", "lessThanOrEqual": "0.9.7", "versionType": "custom" } ], "defaultStatus": "unaffected" } ], "descriptions": [ { "lang": "en", "value": "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. \n\n\nNote: Software versions which have reached End of Technical Support (EoTS) are not evaluated.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. \n\n\nNote: Software versions which have reached End of Technical Support (EoTS) are not evaluated." } ] } ], "tags": [ "x_F5" ], "references": [ { "url": "https://my.f5.com/manage/s/article/K000161377", "tags": [ "vendor-advisory" ] } ], "metrics": [ { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV3_1": { "version": "3.1", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH", "baseSeverity": "HIGH", "baseScore": 8.1, "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H" } }, { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV4_0": { "version": "4.0", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "NONE", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "baseSeverity": "CRITICAL", "baseScore": 9.2, "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N" } } ], "credits": [ { "lang": "en", "value": "\"F5 acknowledges Mufeed VH of Winfunc Research, Nebula Security (@nebusecurity), and Vexera AI for bringing this issue to our attention and following the highest standards of coordinated disclosure.\"", "type": "reporter" } ], "source": { "discovery": "EXTERNAL" }, "x_generator": { "engine": "F5 SIRTBot v1.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-05-22T00:00:00+00:00", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "role": "CISA Coordinator", "version": "2.0.3", "id": "CVE-2026-9256" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-23T03:55:52.757Z" } }, { "title": "CVE Program Container", "references": [ { "url": "http://www.openwall.com/lists/oss-security/2026/05/22/14" }, { "url": "https://lists.debian.org/debian-lts-announce/2026/06/msg00023.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2026-06-18T05:35:40.986Z" } }, { "affected": [ { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:10.2" ], "defaultStatus": "affected", "packageName": "nginx", "product": "Red Hat Enterprise Linux 10", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "2:1.26.3-6.el10_2.4", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:enterprise_linux:8" ], "defaultStatus": "affected", "packageName": "nginx:1.24", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "8100020260611094050.489197e6", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:enterprise_linux:9" ], "defaultStatus": "affected", "packageName": "nginx:1.24", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "9080020260610161820.9", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:enterprise_linux:9" ], "defaultStatus": "affected", "packageName": "nginx", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "2:1.20.1-28.el9_8.3", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:enterprise_linux:9" ], "defaultStatus": "affected", "packageName": "nginx:1.26", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "9080020260609152155.9", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:discovery:2::el9" ], "defaultStatus": "affected", "packageName": "discovery/discovery-ui-rhel9", "product": "Red Hat Discovery 2", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1782756541", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:hummingbird:1" ], "defaultStatus": "affected", "packageName": "nginx-main", "product": "Red Hat Hardened Images", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1.30.2-1.hum1", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:rhui:5::el9" ], "defaultStatus": "affected", "packageName": "rhui5/cds-kubernetes-rhel9", "product": "Red Hat Update Infrastructure 5", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1784794818", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:rhui:5::el9" ], "defaultStatus": "affected", "packageName": "rhui5/cds-rhel9", "product": "Red Hat Update Infrastructure 5", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1784794778", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:rhui:5::el9" ], "defaultStatus": "affected", "packageName": "rhui5/rhua-rhel9", "product": "Red Hat Update Infrastructure 5", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1784795076", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:rhui:5::el9" ], "defaultStatus": "affected", "packageName": "rhui5/cds-kubernetes-tp-rhel9", "product": "Red Hat Update Infrastructure 5", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1787241211", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:rhui:5::el9" ], "defaultStatus": "affected", "packageName": "rhui5/rhua-tp-rhel9", "product": "Red Hat Update Infrastructure 5", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1787241260", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:insights_proxy:1" ], "defaultStatus": "affected", "packageName": "insights-proxy/insights-proxy-container-rhel9", "product": "Red Hat Lightspeed proxy 1", "vendor": "Red Hat" } ], "datePublic": "2026-05-22T14:11:41.877Z", "descriptions": [ { "lang": "en", "value": "A flaw was found in the ngx_http_rewrite_module module of NGINX. When a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures and a replacement string that references multiple such captures in a redirect or arguments context, an unauthenticated attacker can send crafted HTTP requests and cause a heap-based buffer overflow in the worker process, potentially allowing code execution or a denial of service by forcing the process to restart." } ], "metrics": [ { "other": { "content": { "namespace": "https://access.redhat.com/security/updates/classification/", "value": "Important" }, "type": "Red Hat severity rating" } }, { "cvssV3_1": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1" }, "format": "CVSS" } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-122", "description": "Heap-based Buffer Overflow", "lang": "en", "type": "CWE" } ] } ], "references": [ { "tags": [ "vdb-entry", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/security/cve/CVE-2026-9256" }, { "name": "RHBZ#2480746", "tags": [ "issue-tracking", "x_refsource_REDHAT" ], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2480746" }, { "tags": [ "x_sadp-csaf-vex" ], "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9256.json" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:29874" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:28921" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:28212" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:28973" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:29151" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:33313" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:20351" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:44481" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:58981" } ], "solutions": [ { "lang": "en", "value": "RHSA-2026:29874: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)" }, { "lang": "en", "value": "RHSA-2026:28921: Red Hat Enterprise Linux AppStream (v. 8)" }, { "lang": "en", "value": "RHSA-2026:28212: Red Hat Enterprise Linux AppStream (v. 9)" }, { "lang": "en", "value": "RHSA-2026:28973: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)" }, { "lang": "en", "value": "RHSA-2026:29151: Red Hat Enterprise Linux AppStream (v. 9)" }, { "lang": "en", "value": "RHSA-2026:33313: Red Hat Discovery 2" }, { "lang": "en", "value": "RHSA-2026:20351: Red Hat Hardened Images" }, { "lang": "en", "value": "RHSA-2026:44481: Red Hat Update Infrastructure 5" }, { "lang": "en", "value": "RHSA-2026:58981: Red Hat Update Infrastructure 5" } ], "timeline": [ { "lang": "en", "time": "2026-05-22T15:00:55.131Z", "value": "Reported to Red Hat." }, { "lang": "en", "time": "2026-05-22T14:11:41.877Z", "value": "Made public." } ], "title": "nginx: ngx_http_rewrite_module: code execution and denial of service", "workarounds": [ { "lang": "en", "value": "To mitigate this vulnerability, use named captures instead of unnamed captures in rewrite definitions.\n\nFor example, the following rewrite directive uses unnamed PCRE capture groups, $1 and $2:\n\n~~~\nrewrite ^/users/([0-9]+)/profile/(.*)$ /profile.php?id=$1&tab=$2 last;\n~~~\n\nTo mitigate this vulnerability for this example, replace $1 and $2 with the appropriate named captures, $user_id and $section:\n\n~~~\nrewrite ^/users/(?[0-9]+)/profile/(?
.*)$ /profile.php?id=$user_id&tab=$section last;\n~~~" } ], "x_adpType": "supplier", "x_generator": { "engine": "sadp-cli 1.0.0" }, "providerMetadata": { "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "shortName": "redhat-SADP", "dateUpdated": "2026-08-25T12:05:55.163Z" } } ] } }