CVE-2026-66046

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Source
https://cve.org/CVERecord?id=CVE-2026-66046
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-66046.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-66046
Downstream
Published
2026-08-18T14:10:05Z
Modified
2026-08-22T03:30:41Z
Severity
  • 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS Calculator
Summary
Expat Denial of Service via storeAtts() Quadratic Complexity
Details

Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.

Database specific 
{
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
        "CWE-407"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66046.json"
}
References

Affected packages

Git / github.com/libexpat/libexpat

Affected ranges

Type
GIT
Repo
https://github.com/libexpat/libexpat
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
92810461043fce37e70079b37ab1f04490a8f039
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "last_affected": "2.8.3"
        },
        {
            "fixed": "2.8.3"
        }
    ],
    "source": [
        "AFFECTED_FIELD",
        "DESCRIPTION"
    ]
}

Affected versions

Other
REC1_0
R_1_95_0
R_1_95_2
R_1_95_3
R_1_95_4
R_1_95_5
R_1_95_6
R_1_95_7
R_1_95_8
R_2_0_0
R_2_0_1
R_2_1_0
R_2_1_1
R_2_2_0
R_2_2_1
R_2_2_10
R_2_2_2
R_2_2_3
R_2_2_4
R_2_2_5
R_2_2_6
R_2_2_7
R_2_2_8
R_2_2_9
R_2_3_0
R_2_4_0
R_2_4_1
R_2_4_2
R_2_4_3
R_2_4_4
R_2_4_5
R_2_4_6
R_2_4_7
R_2_4_8
R_2_4_9
R_2_5_0
R_2_6_0
R_2_6_1
R_2_6_2
R_2_6_3
R_2_6_4
R_2_7_0
R_2_7_1
R_2_7_2
R_2_7_3
R_2_7_4
R_2_7_5
R_2_8_0
R_2_8_1
R_2_8_2
V1990307
V19981122
V19981231
V19990109
V19990425
V19990626
V19990709
V19990728
V19991013
V1_0
V1_1
V20000512
beta2
beta3
beta4
jclark-orig
libexpat-alpha-1
sourceforge_init
start

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-66046.json"