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{"bugzilla": {"description": "expat: expat: Denial of Service via NULL pointer dereference in external entity parsing", "id": "2562538", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2562538"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.9", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-476", "details": ["libexpat through 2.9.0 contains a NULL pointer dereference vulnerability in externalEntityInitProcessor2() in lib/xmlparse.c that mishandles the XML_TOK_NONE token from empty input. Attackers who control stream chunking can force an empty non-final first parse on an external entity subparser, causing a later parse to crash the application.", "A flaw was found in expat. A remote attacker who controls input stream chunking can trigger a NULL pointer dereference by forcing an empty initial parse on an external entity subparser. Successful exploitation causes the application to crash, resulting in a Denial of Service (DoS)."], "mitigation": {"lang": "en:us", "value": "Avoid enabling external entity / DTD processing for untrusted XML; prefer parsers configured without external entity resolution. Do not expose stream-chunked XML parse APIs to untrusted clients. Restrict network access to XML-processing services ([CME-202](https://cmetaxonomy.org/entries/CME-202.html), [CME-203](https://cmetaxonomy.org/entries/CME-203.html)). Upgrade to libexpat 2.10.0 or later when available."}, "name": "CVE-2026-117610", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "expat", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "compat-expat1", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "expat", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "expat", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "expat", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "mingw-expat", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "xmlrpc-c", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "expat", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "expat", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-10-28T02:03:18Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-117610\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-117610\nhttps://github.com/libexpat/libexpat\nhttps://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L3468-L3510\nhttps://github.com/libexpat/libexpat/commit/7b0d50e4b1d16fafd55876260701e04279a7489d\nhttps://github.com/libexpat/libexpat/pull/1444\nhttps://www.vulncheck.com/advisories/libexpat-through-2.9.0-null-pointer-dereference-via-external-entity-subparser"], "statement": "This vulnerability is rated Moderate. Confirmed impact is denial of service (NULL dereference / crash) when an empty non-final first parse is performed on an external-entity subparser. Red Hat scores CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (5.9): Attack Complexity is High because exploitation needs uncommon stream-chunking behavior together with external entity parsing, which is not the default posture for most RHEL XML consumers. Hardening (ASLR/NX/FORTIFY/SELinux) does not prevent the crash DoS; Availability remains High. No confidentiality or integrity impact is demonstrated.", "threat_severity": "Moderate"}

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