How severe is CVE-2021-27459?

CVE-2021-27459 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-27459 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27459?

CVE-2021-27459 primarily affects Emerson X-stream Enhanced Xegp Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-27459?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-27459 published?

CVE-2021-27459 was published on 2021-05-20 and last updated on 2026-06-17.

CVE-2021-27459

CVE-2021-27459 is a critical-severity vulnerability in Emerson X-stream Enhanced Xegp Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-434.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Emerson X-stream Enhanced Xegp Firmware
Published: 2021-05-20
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-27459?: 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.
How severe is CVE-2021-27459?: CVE-2021-27459 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-27459 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27459?: CVE-2021-27459 primarily affects Emerson X-stream Enhanced Xegp Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-27459?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-27459 published?: CVE-2021-27459 was published on 2021-05-20 and last updated on 2026-06-17.

References

https://us-cert.cisa.gov/ics/advisories/icsa-21-138-01

Affected products (4)

cpe:2.3:o:emerson:x-stream_enhanced_xegp_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:emerson:x-stream_enhanced_xegk_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:emerson:x-stream_enhanced_xefd_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:emerson:x-stream_enhanced_xexf_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Emerson X-stream Enhanced Xegp Firmware

CVE-2021-27461 — High (CVSS 7.5): A vulnerability has been found in multiple revisions of Emerson Rosemount X-STREAM Gas Analyzer. The affected webserver…
CVE-2021-27457 — High (CVSS 7.5): A vulnerability has been found in multiple revisions of Emerson Rosemount X-STREAM Gas Analyzer. The affected products…
CVE-2020-27254 — High (CVSS 7.5): Emerson Rosemount X-STREAM Gas AnalyzerX-STREAM enhanced XEGP, XEGK, XEFD, XEXF – all revisions, The affected…
CVE-2021-27467 — Medium (CVSS 6.1): A vulnerability has been found in multiple revisions of Emerson Rosemount X-STREAM Gas Analyzer. The affected…
CVE-2021-27465 — Medium (CVSS 6.1): A vulnerability has been found in multiple revisions of Emerson Rosemount X-STREAM Gas Analyzer. The affected…
CVE-2021-27463 — Medium (CVSS 5.3): A vulnerability has been found in multiple revisions of Emerson Rosemount X-STREAM Gas Analyzer. The affected…

All CVEs affecting Emerson X-stream Enhanced Xegp Firmware →

Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

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CVE-2026-81780 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in Hash Form <= 1.4.2 versions.

Browse all CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities →