CVE-2011-1889
CVE-2011-1889 is a security flaw in Microsoft Forefront Threat Management Gateway (TMG). Attackers can run their own code on Microsoft Forefront Threat Management Gateway (TMG). The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 3 Mar 2022.[1]
Microsoft Forefront Threat Management Gateway (TMG) is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Microsoft has published a fix or advice.
Description
CISA calls it a forefront TMG remote code execution in Microsoft Forefront Threat Management Gateway (TMG). In its words: “A remote code execution vulnerability exists in the Forefront Threat Management Gateway (TMG) Firewall Client Winsock provider that could allow code execution in the security context of the client application.”[1]
The CVE record adds: “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."”[2]
The underlying weakness is memory buffer error (CWE-119), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Microsoft’s advisory has them[3]. CISA names the product as Microsoft Forefront Threat Management Gateway (TMG).
Most families won’t have Microsoft Forefront Threat Management Gateway (TMG); it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 3 Mar 2022, 3,913 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 24 Mar 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 49%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Microsoft has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Microsoft Forefront Threat Management Gateway (TMG) is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 24 Mar 2022 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 49%.[4] |
See also
Other Microsoft flaws
- CVE-2026-96951, Microsoft Windows: command injection ·
- CVE-2026-65660, Microsoft SharePoint: code injection ·
- CVE-2026-85880, Microsoft Windows: heap-based buffer overflow ·
- CVE-2026-81963, Microsoft Windows: link following ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
Other memory buffer error flaws
- CVE-2026-88779, Citrix NetScaler: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88772, Citrix NetScaler: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88771, Citrix NetScaler: improper input validation ·
- CVE-2026-8452, Citrix NetScaler ADC and NetScaler Gateway: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2009-3459, Adobe Acrobat and Reader: heap-based buffer overflow ·
Added the same day
- CVE-2022-20708, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20703, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20701, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20700, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20699, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
Every Microsoft flaw on CISA’s list · Everything added in March 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Forefront TMG Remote Code Execution Vulnerability”. Known Exploited Vulnerabilities Catalog, added 3 Mar 2022.
- ^ National Institute of Standards and Technology. “CVE-2011-1889 Detail”. National Vulnerability Database, published 16 Jun 2011.
- ^ Microsoft. Advisories and fixes: docs.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.490, percentile 98.9, 31 Oct 2026.
- CVE Program. “CVE-2011-1889”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.