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.
CVE-2026-77214
Score 8.2 from GitHub Security Advisory (severity: HIGH) published 2026-10-07. A secondary CVSS source baseline 8.2; sources differ by 0.0.
- High severity, but no confirmed exploitation yet
An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.
- CVSS v3
- 8.2
- EG Score
- 8.2HIGHhigh confidence
- EG Risk
- 41EG Risk 41/100CISA SSVC
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity82% × 45%Exploitation0% × 40%Automatability30% × 15%CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).Action: An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release. - EPSS PROB
- —
- EPSS %ILE
- —
- KEV
- Not listed
CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).
An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.
Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table
Published
October 7, 2026
Last Modified
October 7, 2026
Advisory Details (3)
Auto-updated Oct 7, 2026libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer | Advisories | VulnCheck
https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffercommit 13c5f63a7f1c (libexpat/libexpat)
Fix landed in libexpat/libexpat commit 13c5f63a7f1c — awaiting tagged release
https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0[CVE-2026-77214] lib: Validate `len` against buffer capacity in `XML_ParseBuffer`
Fix merged in libexpat/libexpat PR #1393 on 2026-09-25 — awaiting tagged release
https://github.com/libexpat/libexpat/pull/1393Vendor Advisories for CVE-2026-77214(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 5× in last 7d / 5× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-10-07 16:12 UTCEG score recompute
- 2026-10-07 16:12 UTCGHSA enrichment
- 2026-10-07 15:30 UTCEG score recompute
- 2026-10-07 14:42 UTCEG score recompute
- 2026-10-07 14:41 UTCMITRE cvelistV5first tracked
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Frequently asked(4)
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Dependency Blast Radius
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