CVE-2021-38191Public exploitNetwork attack vector

Service interruption via wrong-thread LocalSet task destruction

Published Aug 8, 2021 · Updated Aug 4, 2024

Race condition in Tokio allows remote attackers to interrupt service by aborting a task spawned on a LocalSet through a JoinHandle. JoinHandle::abort drops an idle task's future on the calling thread rather than the LocalSet thread, allowing non-Send Rc or RefCell state to be destroyed from the wrong thread. Exploitation requires an application path through which remote input triggers the abort while the task is idle, and the resulting race can interrupt the application.

CVSS severity5.9
Medium
EPSS probability0.84%
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 Tokio allows remote attackers to interrupt service by aborting a task spawned on a LocalSet through a JoinHandle. JoinHandle::abort drops an idle task's future on the calling thread rather than the LocalSet thread, allowing non-Send Rc or RefCell state to be destroyed from the wrong thread. Exploitation requires an application path through which remote input triggers the abort while the task is idle, and the resulting race can interrupt the application.

The record

CVE
CVE-2021-38191
Published
Aug 8, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-362, CWE-366, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.9GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-366Race Condition within a Thread
T1499.004Application or System Exploitation

Public exploit references

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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