CVE-2023-36802
CVE-2023-36802 is a security flaw in Microsoft Streaming Service Proxy. Someone who already has a foothold can use Microsoft Streaming Service Proxy to take full control of the machine. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 12 Sep 2023.[1]
Microsoft Streaming Service Proxy 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. Fixed in version 10.0.17763.4851, 10.0.20348.1970, 10.0.22000.2416 and 10.0.19044.3448 and others.
Description
CISA calls it a privilege escalation in Microsoft Streaming Service Proxy. In its words: “Microsoft Streaming Service Proxy contains an unspecified vulnerability that allows for privilege escalation.”[1]
The underlying weakness is use after free (CWE-416), in MITRE’s list of common software weaknesses.[2]
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| Windows 10 Version 1809 | 10.0.17763.4851 |
| Windows Server 2019 | 10.0.17763.4851 |
| Windows Server 2019 (Server Core installation) | 10.0.17763.4851 |
| Windows Server 2022 | 10.0.20348.1970 |
| Windows 11 version 21H2 | 10.0.22000.2416 |
| Windows 10 Version 21H2 | 10.0.19044.3448 |
| Windows 11 version 22H2 | 10.0.22621.2283 |
| Windows 10 Version 22H2 | 10.0.19045.3448 |
Most families won’t have Microsoft Streaming Service Proxy; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 12 Sep 2023, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 3 Oct 2023 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 28%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Microsoft has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Microsoft Streaming Service Proxy 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 (fixed in version 10.0.17763.4851, 10.0.20348.1970, 10.0.22000.2416 and 10.0.19044.3448 and others), or not in use. CISA gave US government agencies until 3 Oct 2023 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 7.8.[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 28%.[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 use after free flaws
- CVE-2026-109619, PHP: stale internal request-state ·
- CVE-2026-109618, PHP: memory corruption ·
- CVE-2020-9715, Adobe Acrobat: use-after-free ·
- CVE-2026-5281, Google Dawn: use-after-free ·
- CVE-2023-43000, Apple devices: use-after-free ·
Added the same day
- CVE-2023-36761, Microsoft Word: information disclosure ·
Every Microsoft flaw on CISA’s list · Everything added in September 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Streaming Service Proxy Privilege Escalation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 12 Sep 2023.
- ^ National Institute of Standards and Technology. “CVE-2023-36802 Detail”. National Vulnerability Database, published 12 Sep 2023.
- ^ Microsoft. Advisories and fixes: msrc.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.279, percentile 98.1, 31 Oct 2026.
- CVE Program. “CVE-2023-36802”. 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.