CVE Intelligence
High Memory corruption exploit reference

CVE-2021-46143 — In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an integer overflow exists for...

In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an integer overflow exists for m_groupSize.

Published Jan 6, 2022 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: mitre

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 3.8% (30-day exploitation probability)+13
  • Technical severity (high)+6
  • CISA SSVC: exploitation "poc"+5

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
3.79%
ahead of 90% of scored CVEs · Oct 14, 2026
Affects
Libexpat Project
Libexpat and 7 more
CVSS base
7.8
High · 4 source(s)
Prioritization reference: 8.1 provisional

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Proof of concept
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — www.openwall.com (NIST National Vulnerability Database)
  • Documented patch — cert-portal.siemens.com (NIST National Vulnerability Database)
  • Documented patch — github.com (NIST National Vulnerability Database)
  • Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Libexpat Project Libexpat, Netapp Active Iq Unified Manager, Netapp Clustered Data Ontap…).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Libexpat Project Libexpat < 2.4.3 Vulnerable NIST National Vulnerability Database
Netapp Active Iq Unified Manager versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp Clustered Data Ontap versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp Hci Baseboard Management Controller version h610cversion h610sversion h615c Vulnerable NIST National Vulnerability Database
Netapp Oncommand Workflow Automation versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp Solidfire & Hci Management Node versions not specified by the source Vulnerable NIST National Vulnerability Database
Siemens Sinema Remote Connect Server < 3.1 Vulnerable NIST National Vulnerability Database
Tenable Nessus < 8.15.3≥ 10.0.0 and < 10.1.1 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.1 CVSS 3.1 High 2.2 5.9 cve@mitre.org via NIST National Vulnerability Database
8.1 CVSS 3.1 High — — mitre via CVE Program (cve.org) e CISA ADP
7.8 CVSS 3.1 High 1.8 5.9 nvd@nist.gov via NIST National Vulnerability Database
7.8 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
6.8 CVSS 2.0 Medium 8.6 6.4 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 8.1 (cve@mitre.org via NIST National Vulnerability Database) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-190 · Integer Overflow or Wraparound

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 3.79%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • SSVC assessment updated
    Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 14, 2026
  • Fix documented
    Oct 14, 2026 · NIST National Vulnerability Database
  • Affected products added · libexpat project/libexpat, netapp/active iq unified manager, netapp/clustered data ontap, netapp/hci baseboard managemen
    Oct 14, 2026 · NIST National Vulnerability Database
  • CVSS changed · 7.8
    Oct 14, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 14, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 14, 2026 · Alertas do Telegram
  • 2022
  • CVE published
    Jan 6, 2022 · mitre

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 14, 2026 – Oct 14, 2026
  • 1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

13 on the record

Elsewhere on this site

Libexpat Project
every CVE for this vendor
Memory corruption
same class
CWE-190
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-103946 SQL Injection 1d
  • CVE-2026-76957 Use After Free in Libexpat Project Libexpat Aug 20, 2026
  • CVE-2026-76956 In libexpat 2.8.2 and 2.8.3 before 2.8.4, misinterpretation of getentropy's return code… Aug 20, 2026
  • CVE-2026-66046 Expat Denial of Service via storeAtts() Quadratic Complexity Aug 18, 2026
  • CVE-2026-72522 Out-of-bounds Read in Libexpat Project Libexpat Aug 10, 2026
  • CVE-2026-57587 SQL Injection in Nessus via Reverse DNS Lookup Jun 25, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2021-46143 is "In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an integer overflow exists for...", rated High. It affects Libexpat (Libexpat Project); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 3.79% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.

Sign in or create an account to comment and suggest corrections.