No exploitation reported

CVE-2021-27459

No exploitation reported by the sources we read.

Published2021-05-20
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

A vulnerability has been found in multiple revisions of Emerson Rosemount X-STREAM Gas Analyzer. The webserver of the affected products allows unvalidated files to be uploaded, which an attacker could utilize to execute arbitrary code.

Timeline

dates in UTC

2021-05-2012:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 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-2021-27459?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-27459?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Emerson x-stream enhanced xefd firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

Emerson x-stream enhanced xegk firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

Emerson x-stream enhanced xegp firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

1 more product in the sources.

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

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

ICSA-21-138-01 CISA4 known affected
ICSA-21-138-01_Emerson Rosemount X-STREAM
X-STREAM enhanced XEGP: all revisions · X-STREAM enhanced XEGK: all revisions · X-STREAM enhanced XEXF: all revisions · +1 more

Full record on NVD

Fix

Mitigation from the vendor CISA ICSA-21-138-01 · 4 productsEmerson recommends users update the firmware of the affected products. A new release that addresses the issues identified in this cybersecurity notification impacting the affected products is available. For information on how to obtain the update, contact TechSupport.Hasselroth@emerson.com
Mitigation from the vendor CISA ICSA-21-138-01 · 4 productsIn addition, Emerson recommends users of affected products continue to utilize current cybersecurity industry best practices and ensure the affected products are connected to a well-protected network and properly segmented from the Internet. For more information see the Emerson Security notificatio…
Mitigation from the vendor CISA ICSA-21-138-01 · 4 productsOne of the cybersecurity best practices should include configuring web browsers to prohibit storage of user information such as login names and passwords.

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
CNAweakness (CWE)CWE-434read 2026-10-23
FIRST EPSSEPSS score1.8 %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: 2021-05-20
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-27459?

Is CVE-2021-27459 actively exploited?

Active exploitation of CVE-2021-27459 has not been confirmed. Its EPSS score was 1.8% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-27459?

CVE-2021-27459 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.

Running ICSA-21-138-01_Emerson? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

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