Threats / Microsoft / CVE-2019-1429
CVE-2019-1429
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Microsoft Internet Explorer vulnerability
Microsoft Internet Explorer memory corruption vulnerability enabling remote code execution with use-after-free and buffer overflow flaws. Actively exploited in the wild.
Verdict
Today item — known-exploited.
A critical memory safety vulnerability in Internet Explorer allows attackers to execute arbitrary code in the user's security context through memory corruption. Active exploitation in the wild elevates risk despite no ransomware association.
CISA KEV Yes · 2021-11-034EPSS 0.7729 (verify live)5CVSS 7.5 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
4 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03).
Probability (EPSS)
EPSS 0.7729 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H) · Affected: Microsoft, Internet Explorer. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-416 Use After Free, CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 722 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious webpage or email containing specially crafted content that triggers memory corruption when processed by Internet Explorer.
Business
Users visiting untrusted websites or opening malicious emails face immediate code execution risk, compromising endpoint security and data confidentiality.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit the use-after-free and buffer overflow conditions to gain code execution within the browser process running under the victim's user privileges.
Business
Attackers obtain persistent access to user credentials, sensitive files, and internal network resources without requiring additional privilege escalation.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish a foothold on the compromised system to deploy secondary payloads, establish command and control, or move laterally within the network.
Business
Organizations face potential data exfiltration, system compromise, and lateral movement threats across their infrastructure.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by microsoftCNA
Credited with finding itResecurity Inc. @resecurity_comfinderAnonymous researcher working with iDefense LabsfinderIvan Fratric of Google Project ZerofinderClément Lecigne of Google’s Threat Analysis Groupfinder
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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