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
“—” beside the score: it is equal to the CVSS score beside it.
Score 8.2 from GitHub Security Advisory (severity: HIGH) published 2026-10-07. The CNA's CVSS baseline 8.2; sources differ by 0.0.
Also known asEUVD-2026-94368 (ENISA EUVD) · GHSA-8xfx-9m5m-pgcp (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 8.2
- EG Score
- 8.2HIGHhigh confidence
- EG Risk
- 52EG Risk 52/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity82% × 45%Impact severity (EG Severity): CVSS 8.2 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.3% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.3%
- EPSS %ILE
- 24th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.2): severity, escalated by confirmed exploitation. This CVE's 8.2 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.2 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 7, 2026
Last Modified
October 27, 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(8)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:92323Red Hat Product SecurityHigh
Red Hat Security Advisory: expat security update
- RHSA-2026:89907Red Hat Product SecurityCritical
Red Hat Security Advisory: Red Hat Update Infrastructure 5.3 security update
- RHSA-2026:88247Red Hat Product SecurityHigh
Red Hat Security Advisory: expat security update
- RHSA-2026:88248Red Hat Product SecurityHigh
Red Hat Security Advisory: expat security update
- RHSA-2026:85985Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
- CVE-2026-77214Microsoft Security Response Center (MSRC)High
libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer
- RHSA-2026:77959Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
- GHSA-8xfx-9m5m-pgcpGitHub Security AdvisoriesHigh
libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c....
Patch Availability(4)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| redhat | expat-0:2.7.3-1.el10_2.7 | 2026-10-22 | redhat |
| redhat | expat-0:2.5.0-6.el9_8.7 | 2026-10-22 | redhat |
| redhat | expat-main-2.9.0-1.hum1 | 2026-10-20 | redhat |
| redhat | expat-main-2.8.5-1.2.hum1 | 2026-10-07 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(3 across 3 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| expat | 2.5.0-1 ... 2.9.0-1 (34 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| expat | 2.7.1-2 ... 2.9.0-1 (18 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| expat | 2.7.1-2 ... 2.8.5-2 (17 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 73× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-27 10:25 UTCEG score recompute
- 2026-10-27 10:25 UTCVendor advisory
- 2026-10-27 10:25 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
- 2026-10-25 14:01 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 45th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 45th percentile
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 45th percentile
- 2026-10-22 11:37 UTCEG score recompute
- 2026-10-22 11:37 UTCVendor advisory
- 2026-10-22 11:37 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 45th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-20 08:13 UTCEG score recompute
- 2026-10-20 08:13 UTCVendor advisory
- 2026-10-20 08:12 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
Show 48 moreShow fewer
- 2026-10-18 03:12 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-13 07:00 UTCEG score recompute
- 2026-10-13 07:00 UTCVendor advisory
- 2026-10-13 07:00 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-12 15:37 UTCEG score recompute
- 2026-10-12 01:10 UTCVendor advisory
- 2026-10-12 01:09 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-11 19:23 UTCEG score recompute
- 2026-10-11 16:39 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-11 13:42 UTCEG score recompute
- 2026-10-11 13:42 UTCVendor advisory
- 2026-10-11 13:42 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-11 02:09 UTCEG score recompute
- 2026-10-11 02:09 UTCVendor advisory
- 2026-10-11 02:09 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-10 14:44 UTCVendor advisory
- 2026-10-10 14:43 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-10 03:22 UTCEG score recompute
- 2026-10-10 03:22 UTCVendor advisory
- 2026-10-10 03:22 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-10 02:40 UTCEG score recompute
- 2026-10-10 02:40 UTCVendor advisory
- 2026-10-10 02:40 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-10 01:20 UTCEG score recompute
- 2026-10-10 01:20 UTCVendor advisory
- 2026-10-10 01:20 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-09 13:58 UTCVendor advisory
- 2026-10-09 13:58 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-09 02:34 UTCEG score recompute
- 2026-10-09 02:34 UTCVendor advisory
- 2026-10-09 02:34 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-08 15:12 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-08 03:34 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-07 16:12 UTCEG score recompute
- 2026-10-07 16:12 UTCGHSA enrichmentGHSA-8xfx-9m5m-pgcp · GitHub severity HIGH · GitHub CVSS 8.2
- 2026-10-07 15:30 UTCEG score recompute
- 2026-10-07 14:42 UTCEG score recomputeFirst assessed: 8.2 HIGH
- 2026-10-07 14:41 UTCMITRE cvelistV5first tracked
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Frequently asked(5)
What is CVE-2026-77214?
When was CVE-2026-77214 made public?
Is CVE-2026-77214 actively exploited?
What is the CVSS score of CVE-2026-77214?
How do I remediate CVE-2026-77214?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-77214
Is Your Infrastructure Affected by CVE-2026-77214?
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