CVE-2021-41973Network attack vector

Service hang via mispositioned HTTP buffer decoding

Published Nov 1, 2021 · Updated Aug 4, 2024

Infinite-loop denial of service in affected Apache MINA releases before 2.1.5 allows remote attackers to hang an HTTP service. HttpServerDecoder.parseHttpRequestHead reads from array offset zero to the buffer limit instead of the current position and remaining bytes, causing extra buffered data to be repeatedly reprocessed. Reachability requires an application to use MINA's HTTP server decoder; the reported consequence is a service hang without data disclosure or modification.

CVSS severity6.5
Medium
EPSS probability4.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite-loop denial of service in affected Apache MINA releases before 2.1.5 allows remote attackers to hang an HTTP service. HttpServerDecoder.parseHttpRequestHead reads from array offset zero to the buffer limit instead of the current position and remaining bytes, causing extra buffered data to be repeatedly reprocessed. Reachability requires an application to use MINA's HTTP server decoder; the reported consequence is a service hang without data disclosure or modification.

The record

CVE
CVE-2021-41973
Published
Nov 1, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache MINA
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 1, 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?

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

  1. Affected versionversion=Apache MINA <2.1.5 changes=[{"at":"2.0.22","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache MINAversion=Apache MINA <2.1.5 changes=[{"at":"2.0.22","status":"unaffected"}]

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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