How severe is CVE-2021-42127?

CVE-2021-42127 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-2021-42127 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 66% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42127?

CVE-2021-42127 affects Ivanti Avalanche. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42127?

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-2021-42127 published?

CVE-2021-42127 was published on 2021-12-07 and last updated on 2026-06-17.

CVE-2021-42127

CVE-2021-42127 is a critical-severity vulnerability in Ivanti Avalanche with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 66% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 66% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Ivanti Avalanche
Published: 2021-12-07
Last modified: 2026-06-17

Description

A deserialization of untrusted data vulnerability exists in Ivanti Avalanche before 6.3.3 using Inforail Service allows arbitrary code execution via Data Repository Service.

Frequently asked questions

What is CVE-2021-42127?: A deserialization of untrusted data vulnerability exists in Ivanti Avalanche before 6.3.3 using Inforail Service allows arbitrary code execution via Data Repository Service.
How severe is CVE-2021-42127?: CVE-2021-42127 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-2021-42127 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 66% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42127?: CVE-2021-42127 affects Ivanti Avalanche. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42127?: 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-2021-42127 published?: CVE-2021-42127 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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