Threats / Microsoft / CVE-2026-21525
CVE-2026-21525
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Windows vulnerability
Microsoft Windows Remote Access Connection Manager contains a NULL pointer dereference vulnerability allowing local denial of service.
Verdict
Today item — known-exploited.
A NULL pointer dereference in Windows Remote Access Connection Manager enables local attackers to crash the service, disrupting remote access connectivity. Exploitation requires local system access and causes service unavailability rather than data compromise.
CISA KEV Yes · 2026-02-105EPSS 0.04956 (verify live)6CVSS 6.23CISA SSVC Exploitation: active · Automatable: no · Impact: partial4
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 2026-02-10).
Probability (EPSS)
EPSS 0.04956 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 6.2 (CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C) · Affected: Microsoft, Windows. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-476 NULL Pointer Dereference — weakness family: Memory safety.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: partialCISA'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 the same day 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 gain local access to a Windows system through initial compromise or legitimate credentials.
Business
An attacker with local system presence can be leveraged for lateral movement or persistence.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger the NULL pointer dereference in Remote Access Connection Manager through a crafted local operation.
Business
The Remote Access Connection Manager service crashes, rendering remote access capabilities unavailable.
3
Lateral reach — past segmentation narrative 3
Attacker
I deny legitimate users and administrators the ability to establish remote connections to the affected system.
Business
Business operations dependent on remote access are disrupted, reducing productivity and administrative control.
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