CVE-2021-31354

Code execution via out-of-bounds license-response parsing

Published Oct 19, 2021 · Updated Sep 17, 2024

Out-of-bounds access in the JAL Client in Juniper Networks Junos OS and Junos OS Evolved allows adjacent attackers to execute code. Its custom-protocol response parser accesses data outside the intended bounds when processing a crafted license-manager response. Exposure requires Network Mode and either control of a JAL License Manager or local-broadcast-domain access; default Standalone Mode is unaffected.

CVSS severity7.1
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds access in the JAL Client in Juniper Networks Junos OS and Junos OS Evolved allows adjacent attackers to execute code. Its custom-protocol response parser accesses data outside the intended bounds when processing a crafted license-manager response. Exposure requires Network Mode and either control of a JAL License Manager or local-broadcast-domain access; default Standalone Mode is unaffected.

The record

CVE
CVE-2021-31354
Published
Oct 19, 2021
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-125, T1203
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=20.1R1-EVO <unspecified
  2. Affected versionversion=unspecified <21.2R2-EVO

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=20.1R1-EVO <unspecified; version=unspecified <21.2R2-EVO
Juniper Networks · Junos OSversion=19.2 <19.2R3-S3; version=19.3 <19.3R3-S3; version=20.1 <20.1R2-S2, 20.1R3-S1; version=20.2 <20.2R3-S2; version=20.3 <20.3R3; version=20.4 <20.4R3; version=21.1 <21.1R2

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.1Juniper NetworksCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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