CVE-2026-118370

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{"bugzilla": {"description": "expat: expat: Denial of Service via integer overflow during XML attribute parsing", "id": "2562544", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2562544"}, "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-787", "details": ["libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document with a start tag carrying over 2^30 attributes to overflow attIndex and nPrefixes, crashing applications or corrupting heap memory.", "A flaw was found in expat. An integer overflow in the XML attribute parsing logic allows a remote attacker to cause memory corruption and a Denial of Service (DoS). By supplying a specially crafted XML document containing an excessively large number of attributes, an attacker can trigger out-of-bounds memory writes, leading to an application crash."], "mitigation": {"lang": "en:us", "value": "Reject oversized or attribute-dense untrusted XML before parsing; multi-gigabyte documents with huge attribute counts are required to hit the overflow. Apply process/cgroup memory limits to XML-handling workloads ([CME-114](https://cmetaxonomy.org/entries/CME-114.html), [CME-704](https://cmetaxonomy.org/entries/CME-704.html)). Isolate XML-facing services and restrict to trusted sources ([CME-202](https://cmetaxonomy.org/entries/CME-202.html)). Upgrade to libexpat 2.10.0 or later when available."}, "name": "CVE-2026-118370", "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": "2026-10-28T02:03:19Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-118370\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-118370\nhttps://github.com/libexpat/libexpat\nhttps://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L4138-L4140\nhttps://github.com/libexpat/libexpat/commit/1bac53c4fc460a03cd9860f39501c7979f6750ae\nhttps://github.com/libexpat/libexpat/commit/621cb2c78b253ee023a86bc91d6ddb048481c04c\nhttps://github.com/libexpat/libexpat/pull/1450\nhttps://www.vulncheck.com/advisories/libexpat-through-2.9.0-integer-overflow-in-storeatts-via-attindex-and-nprefixes"], "statement": "This vulnerability is rated Moderate. A signed integer overflow in storeAtts() can lead to process crash; reliable confidentiality/integrity compromise is not demonstrated on Red Hat platforms. 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 triggering the overflow requires an extreme, multi-gigabyte XML payload with on the order of 2^30 attributes\u2014typically blocked by practical network/memory limits before parse completes. NVD\u2019s higher score (AC:L and I:L) is acknowledged; RH retains AC:H and I:N given payload prerequisites and platform allocator hardening (CME-117), while keeping A:H for crash/DoS.", "threat_severity": "Moderate"}

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