CVE-2026-77214

CVE Enrichment

CVSS: 8.3 HIGH
EPSS: 0.55%
EPSS Percentile: 44.44%
CISA KEV: Not listed

Description

libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER. A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap memory to the calling application, recovering heap pointers, libc function pointers, and code pointers sufficient to defeat ASLR and build further exploitation primitives.

Technical Details

CVSS Version: 4.0
CNA / NVD Source: disclosure@vulncheck.com
Published: 07-Oct-2026 22:17
Last Modified: 10-Oct-2026 10:17
EPSS Date: 2026-10-13
CWE: CWE-125

CVSS Vector


            CVSS:4.0                            AV:N /
                            AC:L /
                            AT:P /
                            PR:N /
                            UI:N /
                            VC:H /
                            VI:N /
                            VA:L /
                            SC:N /
                            SI:N /
                            SA:N /
                            E:X /
                            CR:X /
                            IR:X /
                            AR:X /
                            MAV:X /
                            MAC:X /
                            MAT:X /
                            MPR:X /
                            MUI:X /
                            MVC:X /
                            MVI:X /
                            MVA:X /
                            MSC:X /
                            MSI:X /
                            MSA:X /
                            S:X /
                            AU:X /
                            R:X /
                            V:X /
                            RE:X /
                            U:X

References

Last enrichment sync: 14-Oct-2026 21:24
Sources: NVD · FIRST EPSS · CISA KEV
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Reported Context (1)

CVE-2026-77214 Microsoft October 2026 Updates Fix 1,411 Flaws, Including Three Zero-Days

CVE (1235)

People (2)

MITRE ATT&CK (1)

Vendors (14)

Products (87)

Tools (1)

Note: Related entities, including threat actors, malware, CVEs, MITRE ATT&CK techniques, vendors, products, tools, countries, and industries, are shown when they appear in the same reporting. Their presence does not necessarily mean they were targeted, compromised, vulnerable, responsible for the activity, or directly involved in the incident.