What is CVE-2011-1889?

CVE-2011-1889 is a critical-severity vulnerability in Microsoft Forefront Threat Management Gateway, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2011-06-16.

How severe is CVE-2011-1889?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2011-1889 known to be exploited?

Yes. CVE-2011-1889 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.

Buffer overflow in Microsoft Forefront Threat Management Gateway

CVE-2011-1889

The NSPLookupServiceNext function in the client in Microsoft Forefront Threat Management Gateway (TMG) 2010 allows remote attackers to execute arbitrary code via vectors involving unspecified requests, aka "TMG Firewall Client Memory Corruption Vulnerability."

Vulnerability class: Buffer Overflow

Published 2011-06-16 · last modified 2026-06-16.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.490 (98.9th percentile), scored 2026-10-18.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.490 · newest: 0.490 · change: 0.000

Affected products

Microsoft Forefront Threat Management Gateway — versions 2010

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-03-03. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-03-24.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

www.securitytracker.com/id (VDB Entry, Third Party Advisory, vdb-entry, Broken Link)
docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-040 (vendor-advisory, Patch, Vendor Advisory)
exchange.xforce.ibmcloud.com/vulnerabilities/67736 (VDB Entry, Third Party Advisory, vdb-entry)
www.securityfocus.com/bid/48181 (VDB Entry, Third Party Advisory, vdb-entry, Broken Link)
secunia.com/advisories/44857 (Broken Link, third-party-advisory)
oval.cisecurity.org/repository/search/definition/oval:org.mitre.oval:def:12642 (Broken Link, signature, vdb-entry)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2011-1889?: CVE-2011-1889 is a critical-severity vulnerability in Microsoft Forefront Threat Management Gateway, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2011-06-16.
How severe is CVE-2011-1889?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2011-1889 known to be exploited?: Yes. CVE-2011-1889 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.