CVE-2021-46828Network attack vector

RPC service denial via idle connection exhaustion

Published Jul 20, 2022 · Updated May 5, 2025

Denial of service in libtirpc before 1.3.3rc1 allows remote attackers to stop RPC request handling through idle TCP connections. svc_run fails to expire idle connections or handle accept returning EMFILE, so descriptor exhaustion drives a tight accept loop that cannot process requests. The attack requires enough idle connections to reach the process file-descriptor limit; affected RPC services then stop handling requests.

CVSS severity7.5
High
EPSS probability2.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in libtirpc before 1.3.3rc1 allows remote attackers to stop RPC request handling through idle TCP connections. svc_run fails to expire idle connections or handle accept returning EMFILE, so descriptor exhaustion drives a tight accept loop that cannot process requests. The attack requires enough idle connections to reach the process file-descriptor limit; affected RPC services then stop handling requests.

The record

CVE
CVE-2021-46828
Published
Jul 20, 2022
Updated
May 5, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, CWE-755, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2022CVE publishedPublication date reported by the CVE source.
  2. May 5, 2025Record 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

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Oracle LinuxCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/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.

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
CWE-755Improper Handling of Exceptional Conditions
T1499.004Application or System Exploitation

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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