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ExploitedIn CISA KEVFix available

CVE-2021-35247

Exploitation confirmed. First attested on 2022-01-21 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2022-01-10
  • Fixed in15.3
  • WeaknessCWE-20

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2022-01-1014:10CVE publishedNVD
  2. 2022-01-21Added to the CISA KEV catalogCISA KEV
  3. 2022-01-21Listed as exploited by GCVEGCVE
  4. 2022-01-21Exploitation first reportedCISA KEV
  5. 2025-01-2920:23SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-35247?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-35247?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Solarwinds serv-u
BranchAffectedFixed in
15.3< 15.315.3

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As SolarWinds, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • SolarWinds Serv-U
    Affected
    • ≥ 15.2.5 and previous versions, < 15.3fixed in 15.3custom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2022-01-25

Fix

  1. Update Solarwinds serv-u to 15.3
  2. CISA’s required action: Apply updates per vendor instructions.due 2022-02-04

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2022-01-21
Patch Due Date
2022-02-04
Ransomware Use
Unknown
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Published
2022-01-10
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-jqwj-9jvg-583v

Frequently asked questions

What is CVE-2021-35247?

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.

Is CVE-2021-35247 actively exploited?

Yes. CVE-2021-35247 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2022-02-04.

What is the CVSS score for CVE-2021-35247?

CVE-2021-35247 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

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Sources for this record