CVE-2021-34527
Microsoft Windows: Print Spooler Remote Code Execution
As of , CVE-2021-34527 in Microsoft Windows is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.
- Exploited
- Yes: CISA listed it on 3 November 2021
- US federal deadline
- 3 May 2022181 days after CISA listed it. US federal civilian agencies must fix it by then.
- Used in ransomware campaigns
- Known
- EPSS score
- 0.99Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
- EPSS when listed
- Not availableCISA listed it before 4 February 2022, where the EPSS files we read begin.
- Public exploit
- 1 Metasploit module
- Fix
- No vendor link in CISA's entry
What CISA says to do
Apply updates per vendor instructions.
CISA's required action
What the flaw is
Microsoft Windows Print Spooler contains an unspecified vulnerability due to the Windows Print Spooler service improperly performing privileged file operations. Successful exploitation allows an attacker to perform remote code execution with SYSTEM privileges. The vulnerability is also known under the moniker of PrintNightmare.
CISA's description
A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. UPDATE July 7, 2021: The security update for Windows Server 2012, Windows Server 2016 and Windows 10, Version 1607 have been released. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. In addition to installing the updates, in order to secure your system, you must confirm that the following registry settings are set to 0 (zero) or are not defined (Note: These registry keys do not exist by default, and therefore are already at the secure setting.), also that your Group Policy setting are correct (see FAQ): HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting) UpdatePromptSettings = 0 (DWORD) or not defined (default setting) Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design.
The CVE record's description, from microsoft, shortened; full text on cve.org
- CVE published
- 2 July 2021
- Assigned by
- microsoft
- CVSS
- 8.8 High (CVSS 3.1, from the CNA)
- CWE-269
- Improper Privilege Management
- CISA SSVC, exploitation
- active
- CISA SSVC, automatable
- no
- CISA SSVC, technical impact
- total
Timeline
- The CVE record was published.
- CISA added it to its list of exploited vulnerabilities.
- The US federal deadline to fix it.
- CISA changed its entry. Deadline moved from 20 July 2021 to 3 May 2022.
Public exploits
Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.
- Metasploit: Print Spooler Remote DLL Injectionexploit module, rank normal
Windows: other exploited entries
| Vulnerability | Product | Our group | Listed | Deadline | EPSS |
|---|---|---|---|---|---|
| CVE-2025-60710Link Following | Microsoft Windows | Patch nowRansomware use, listed within a year | 0.05 | ||
| CVE-2008-4250Buffer Overflow | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.99; verified Exploit-DB entry | 0.99 | ||
| CVE-2008-0015Video ActiveX Control Remote Code Execution | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.77; verified Exploit-DB entry | 0.77 | ||
| CVE-2013-3918Out-of-Bounds Write | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.74; verified Exploit-DB entry | 0.74 | ||
| CVE-2010-2568Remote Code Execution | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.91; verified Exploit-DB entry | 0.91 | ||
| CVE-2015-0016TS WebProxy Directory Traversal | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.76; verified Exploit-DB entry | 0.76 | ||
| CVE-2015-2426Adobe Type Manager Library Remote Code Execution | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.87; verified Exploit-DB entry | 0.87 | ||
| CVE-2014-6332Object Linking & Embedding (OLE) Automation Array Remote Code Execution | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.95; verified Exploit-DB entry | 0.95 | ||
| CVE-2017-0146SMB Remote Code Execution | Microsoft Windows | Patch this weekRansomware use; Metasploit module; EPSS 0.90; verified Exploit-DB entry | 0.90 | ||
| CVE-2014-4114Object Linking & Embedding (OLE) Remote Code Execution | Microsoft Windows | Patch this weekMetasploit module; EPSS 0.82; verified Exploit-DB entry | 0.82 |
Read further
- CVE recordcve.org
- NVD entrynvd.nist.gov
- CISA's catalogcisa.gov
- EPSS for this CVEapi.first.org