Threats / Microsoft / CVE-2011-1889
CVE-2011-1889
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Forefront Threat Management Gateway (TMG) vulnerability
A remote code execution vulnerability in Microsoft Forefront TMG Firewall Client Winsock provider allows attackers to execute code within the security context of client applications.
Verdict
Today item — known-exploited.
This buffer overflow vulnerability in the Winsock provider enables remote code execution with high exploitability. Active exploitation in the wild and an EPSS score of 0.88 indicate significant real-world risk to TMG deployments.
CISA KEV Yes · 2022-03-034EPSS 0.48368 (verify live)5CVSS 9.8 (CISA)3CISA SSVC Exploitation: active · Automatable: yes · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
1 independent public report 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 2022-03-03).
Probability (EPSS)
EPSS 0.48368 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) · Affected: Microsoft, Forefront Threat Management Gateway (TMG). 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-119 Memory Buffer Bounds Error — 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: yes · 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 3913 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 network packet targeting the Winsock provider to trigger a buffer overflow.
Business
Client systems running TMG Firewall Client become compromised, potentially exposing internal network access and sensitive data.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I deliver the exploit through network traffic that reaches the vulnerable Winsock provider on the client.
Business
Attackers gain code execution in the context of client applications, enabling lateral movement and privilege escalation within the organization.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary code with the privileges of the affected client application.
Business
Operational security is compromised as attackers establish persistent access and exfiltrate data from protected network segments.
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