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CVE-2021-35211

Serv-U Remote Memory Escape Vulnerability

CRITICAL
10
CVSS Score
Published: July 14, 2021 at 08:55 PM UTC
Updated: June 17, 2026 at 03:57 AM UTC
1 product affected across 1 vendorServ-U

Using Serv-U Managed File Transfer Server and Serv-U Secured FTP by SolarWinds?

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Severity
CRITICAL10
Exploitation
CISA KEV
Exploit prediction
EPSS 91%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score91.2%

EPSS (Exploit Prediction Scoring System) estimates a 91.2% chance this CVE is exploited in the wild within the next 30 days — higher than 100% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

SolarWinds Serv-U contains an unspecified memory escape vulnerability which can allow for remote code execution.

Required Action
Apply updates per vendor instructions.
Ransomware Use
Known
Added to KEV
Nov 3, 2021
Remediation Due
Nov 17, 2021
1810 days overdue
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-35211

Description

Microsoft discovered a remote code execution (RCE) vulnerability in the SolarWinds Serv-U product utilizing a Remote Memory Escape Vulnerability. If exploited, a threat actor may be able to gain privileged access to the machine hosting Serv-U Only. SolarWinds Serv-U Managed File Transfer and Serv-U Secure FTP for Windows before 15.2.3 HF2 are affected by this vulnerability.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Serv-U· Solarwinds
95%
v < 15.2.3SolarWinds Serv-U ≤ v < 15.2.3 HF115.2.315.2.3 hotfix1SolarWinds Serv-U
Affected range stops below 15.2.3, so it looks safe — our inference, not a vendor statement
Affected range stops below 15.2.3 HF1, so it looks safe — our inference, not a vendor statement

References (3)

x_refsource_MISCPatchVendor Advisory
Source: [email protected]
https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit
x_refsource_MISCPatchVendor Advisory
Source: [email protected]
https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35211
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35211

SSVC — Action Prioritization

SSVCActiveNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

10CRITICAL[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-787

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