CVE-2021-43045Network attack vector

Application crash via unbounded decoded string allocation

Published Jan 6, 2022 · Updated Aug 4, 2024

Resource exhaustion in Apache Avro .NET SDK 1.10.2 and earlier allows remote attackers to crash consuming applications with invalid input. BinaryDecoder.ReadString trusts the decoded string length and passes an extreme value to ArrayPool.Rent or ReadBytes without an upper-bound check. The attacker must cause a consuming application to decode a malformed Avro string; the resulting memory exhaustion interrupts that application without reported data disclosure or modification.

CVSS severity7.5
High
EPSS probability2.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Resource exhaustion in Apache Avro .NET SDK 1.10.2 and earlier allows remote attackers to crash consuming applications with invalid input. BinaryDecoder.ReadString trusts the decoded string length and passes an extreme value to ArrayPool.Rent or ReadBytes without an upper-bound check. The attacker must cause a consuming application to decode a malformed Avro string; the resulting memory exhaustion interrupts that application without reported data disclosure or modification.

The record

CVE
CVE-2021-43045
Published
Jan 6, 2022
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Avro
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 6, 2022CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=Apache Avro <=1.10.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Avroversion=Apache Avro <=1.10.2

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS: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-770Allocation of Resources Without Limits or Throttling
T1499.004Endpoint Denial of Service: Application 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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo