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CVE-2021-35247

Improper Input Validation Vulnerability in Serv-U

MEDIUM
5.3
CVSS Score
Published: January 7, 2022 at 10:39 PM UTC
Updated: June 17, 2026 at 03:57 AM UTC
1 product affected across 1 vendorServ-U

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Severity
MEDIUM5.3
Exploitation
CISA KEV
Exploit prediction
EPSS 3%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score3.5%

EPSS (Exploit Prediction Scoring System) estimates a 3.5% chance this CVE is exploited in the wild within the next 30 days — higher than 89% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

SolarWinds Serv-U versions 15.2.5 and earlier contain an improper input validation vulnerability that allows attackers to build and send queries without sanitization.

Required Action
Apply updates per vendor instructions.
Ransomware Use
Unknown
Added to KEV
Jan 21, 2022
Remediation Due
Feb 4, 2022
1728 days overdue
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-35247

Description

Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized. SolarWinds has updated the input mechanism to perform additional validation and sanitization. Please Note: No downstream affect has been detected as the LDAP servers ignored improper characters. To insure proper input validation is completed in all environments. SolarWinds recommends scheduling an update to the latest version of Serv-U.

Affected

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

Serv-U· Solarwinds
95%
v < 15.315.2.5 and previous versions ≤ v < 15.315.2.5 and previous versions
Affected range stops below 15.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-3_release_notes.htm
x_refsource_MISCBroken LinkVendor Advisory
Source: [email protected]
https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35247
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35247

SSVC — Action Prioritization

SSVCActiveNot automatablePartial impact

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

CVSS

5.3MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-20NVD-CWE-noinfo

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