ZeroDay Findings
Sign inSign up

Findings

CVE-2026-77214

libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c.

Published Oct 7, 2026 · corrected/updated Oct 16, 2026 · evidence confidence high

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.

Grounded briefings

Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.

Executive

CVE-2026-77214 is a unknown public vulnerability record for this product. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.

System administrator

Identify whether this product is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: expat (2.5.0-1, 2.5.0-1+deb12u1, 2.5.0-1+deb12u2); expat (0 → 2.9.0-1~deb13u1); expat (0 → 2.9.0-1). Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.

Security analyst

Signals on file: no CVSS/EPSS yet. It is not currently listed in the CISA Known Exploited catalog. Sources contributing to this record: cve_org, debian, osv. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.

Exploitation and remediation

  • Exploitation evidence

    Not listed as known exploited in CISA KEV. Not in the CISA KEV catalog.

  • Patch and remediation

    No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Technology hubs

Debian

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 7, 2026 · OSV.dev

    Detected

    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 t

  2. Oct 16, 2026 · OSV.dev

    Fix available

    expat fixed in 2.9.0-1~deb13u1; expat fixed in 2.9.0-1

  3. Oct 16, 2026 · OSV.dev

    Fix available

    expat fixed in 2.9.0-1~deb13u1

  4. Oct 16, 2026 · OSV.dev

    Fix available

    expat fixed in 2.9.0-1

  5. Oct 16, 2026 · OSV.dev

    Updated

    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 t

Affected

  • Debian:12 expat2.5.0-1, 2.5.0-1+deb12u1, 2.5.0-1+deb12u2
  • Debian:13 expat0 → 2.9.0-1~deb13u1
  • Debian:14 expat0 → 2.9.0-1

Sources

References