CVE-2021-21363

Privilege escalation via temporary-directory creation race

Published Mar 11, 2021 · Updated Aug 3, 2024

Race condition in Swagger Codegen before 2.4.19 allows local users to control generated output through a shared temporary directory. Generator.getTmpFolder deletes a File.createTempFile result and separately recreates its pathname as a directory, leaving a race for another user to claim it. Exploitation requires a collocated user on a Unix-like host to win the race; attacker-written source in outputFolder runs when the generated code is executed.

CVSS severity9.3
Critical
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Swagger Codegen before 2.4.19 allows local users to control generated output through a shared temporary directory. Generator.getTmpFolder deletes a File.createTempFile result and separately recreates its pathname as a directory, leaving a race for another user to claim it. Exploitation requires a collocated user on a Unix-like host to win the race; attacker-written source in outputFolder runs when the generated code is executed.

The record

CVE
CVE-2021-21363
Published
Mar 11, 2021
Updated
Aug 3, 2024
Vendor
SmartBear
Product
Swagger Codegen
Classifications
CWE-379, CWE-378, T1574
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 2.4.19

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

SmartBear · Swagger Codegenversion=< 2.4.19

Published CVSS scores

9.3GitHubCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

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.

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No observations available

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

Weakness, pattern, technique

CWE-379Creation of Temporary File in Directory with Insecure Permissions
CWE-378Creation of Temporary File With Insecure Permissions
T1574Hijack Execution Flow

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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