How severe is CVE-2021-42133?

CVE-2021-42133 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2021-42133 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42133?

CVE-2021-42133 affects Ivanti Avalanche. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42133?

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

When was CVE-2021-42133 published?

CVE-2021-42133 was published on 2021-12-07 and last updated on 2026-06-17.

CVE-2021-42133

CVE-2021-42133 is a high-severity vulnerability in Ivanti Avalanche with a CVSS 3.x base score of 8.1. 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-829.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 5.5
EPSS exploit prediction: 3% (85th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-829
Affected product: Ivanti Avalanche
Published: 2021-12-07
Last modified: 2026-06-17

Description

An exposed dangerous function vulnerability exists in Ivanti Avalanche before 6.3.3 allows an attacker with access to the Inforail Service to perform an arbitrary file write.

Frequently asked questions

What is CVE-2021-42133?: An exposed dangerous function vulnerability exists in Ivanti Avalanche before 6.3.3 allows an attacker with access to the Inforail Service to perform an arbitrary file write.
How severe is CVE-2021-42133?: CVE-2021-42133 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2021-42133 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42133?: CVE-2021-42133 affects Ivanti Avalanche. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42133?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-42133 published?: CVE-2021-42133 was published on 2021-12-07 and last updated on 2026-06-17.

References

https://forums.ivanti.com/s/article/Security-Alert-CVE-s-Addressed-in-Avalanche-6-3-3

Affected products (1)

cpe:2.3:a:ivanti:avalanche:*:*:*:*:*:*:*:*

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