Public proof of conceptFix available

CVE-2021-27198

Q: Is CVE-2021-27198 actively exploited?

Active exploitation of CVE-2021-27198 has not been confirmed. Its EPSS score was 13.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-27198?

CVE-2021-27198 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

A public proof of concept exists; no exploitation attested.

Published2021-02-26
Fixed in11.1a
WeaknessCWE-434

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

An issue was discovered in Visualware MyConnection Server before v11.1a. Unauthenticated Remote Code Execution can occur via Arbitrary File Upload in the web service when using a myspeed/sf?filename= URI. This application is written in Java and is thus cross-platform. The Windows installation runs as SYSTEM, which means that exploitation gives one Administrator privileges on the target system.

Timeline

dates in UTC

2021-02-2623:15CVE publishedNVD
2026-10-2319:23First public proof of conceptPoC-in-GitHub
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 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-2021-27198?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-27198?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Visualware myconnection server

Branch	Affected	Fixed in	Source
11.1	< 11.1a	11.1a	NVD

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

Fix

Update Visualware myconnection server to 11.1a

Advisories and patches

myconnectionserver.visualware.comVendor Advisory
myconnectionserver.visualware.comRelease Notes · Vendor Advisory

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifiedrwincey/CVE-2021-27198

Sources

NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.010read 2026-10-23
NVDweakness (CWE)CWE-434read 2026-10-23
FIRST EPSSEPSS score13.6 %read 2026-10-23
PoC-in-GitHubproof of concept1read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2021-02-26
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-27198?

Is CVE-2021-27198 actively exploited?

Active exploitation of CVE-2021-27198 has not been confirmed. Its EPSS score was 13.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-27198?

CVE-2021-27198 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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