How severe is CVE-2021-33199?

CVE-2021-33199 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-2021-33199 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33199?

CVE-2021-33199 affects Expressionengine. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33199?

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-2021-33199 published?

CVE-2021-33199 was published on 2021-08-12 and last updated on 2026-06-17.

CVE-2021-33199

CVE-2021-33199 is a critical-severity vulnerability in Expressionengine 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-20.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Expressionengine
Published: 2021-08-12
Last modified: 2026-06-17

Description

In Expression Engine before 6.0.3, addonIcon in Addons/file/mod.file.php relies on the untrusted input value of input->get('file') instead of the fixed file names of icon.png and icon.svg.

Frequently asked questions

What is CVE-2021-33199?: In Expression Engine before 6.0.3, addonIcon in Addons/file/mod.file.php relies on the untrusted input value of input->get('file') instead of the fixed file names of icon.png and icon.svg.
How severe is CVE-2021-33199?: CVE-2021-33199 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-2021-33199 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33199?: CVE-2021-33199 affects Expressionengine. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33199?: 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-2021-33199 published?: CVE-2021-33199 was published on 2021-08-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:expressionengine:expressionengine:*:*:*:*:*:*:*:*

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