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Vulnerability record · CVE-2021-42127 · published 7 December 2021

CVE-2021-42127: Ivanti Avalanche Inforail Service deserialization RCE

Ivanti · Avalanche

Ivanti Avalanche before 6.3.3 deserializes untrusted data in the Inforail Service, reachable through the Data Repository Service, allowing arbitrary code execution. The flaw is remotely exploitable without authentication or user interaction, making it a serious pre-auth RCE in an enterprise mobility management product.

9.8 CVSS 3.1 Critical EPSS 66% · top 0.8% CWE-502 · Deserialization of untrusted data
9.8CVSS 3.1 base score, v2 7.5
66%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 19 September 2026. Confidence: medium.

critical priorityPre-auth network-reachable RCE with CVSS 9.8 and very high EPSS, though not yet in KEV.

What it is

Ivanti Avalanche before 6.3.3 deserializes untrusted data in the Inforail Service, reachable through the Data Repository Service, allowing arbitrary code execution. The flaw is remotely exploitable without authentication or user interaction, making it a serious pre-auth RCE in an enterprise mobility management product.

Impact

An unauthenticated attacker can execute arbitrary code on the Avalanche server, likely with the privileges of the affected service. That yields full compromise of the management platform and any managed devices or data it controls.

Attack surface

Reached over the network via the Inforail Service and Data Repository Service endpoints; the CVSS vector AV:N/AC:L/PR:N/UI:N indicates no authentication and no user interaction are required.

Exploitation

Not listed in CISA KEV and no ransomware association is documented, but EPSS is 0.65833 (99.2nd percentile), indicating a high predicted likelihood of exploitation. References are vendor advisories only, with no public exploit or PoC tags supplied.

What to do

  • Upgrade Ivanti Avalanche to 6.3.3 or later per the vendor advisory.
  • If immediate patching is not possible, restrict network access to the Inforail and Data Repository Service ports to trusted hosts only.
  • Segment the Avalanche server from general user networks and limit inbound access from the internet.
  • Monitor vendor advisories for updated guidance and any backported fixes for older branches.

Detection

  • Hunt for unexpected child processes spawned by the Avalanche/Inforail service, especially command shells or scripting interpreters.
  • Monitor network traffic to Inforail and Data Repository Service endpoints for anomalous serialized payloads or unusual source hosts.
  • Alert on deserialization-related errors or crashes in Avalanche service logs.
  • Baseline normal service behavior and flag deviations such as new outbound connections from the Avalanche host.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-42127), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.