CVE-2021-25641Public exploitNetwork attack vector

Pre-auth RCE via attacker-selected deserializer

Published May 29, 2021 · Updated Aug 3, 2024

Deserialization flaw in Apache Dubbo 2.6.x before 2.6.9 and 2.7.x before 2.7.8 allows remote attackers to execute code. Serialization.getSerialization validates requested IDs only for Java-family serializers, so a crafted preamble can select Kryo, FST, or native Hessian. No authentication or user interaction is required, but a weak deserializer and a usable gadget chain must be present in the provider classpath.

CVSS severity9.8
Critical
EPSS probability21.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deserialization flaw in Apache Dubbo 2.6.x before 2.6.9 and 2.7.x before 2.7.8 allows remote attackers to execute code. Serialization.getSerialization validates requested IDs only for Java-family serializers, so a crafted preamble can select Kryo, FST, or native Hessian. No authentication or user interaction is required, but a weak deserializer and a usable gadget chain must be present in the provider classpath.

The record

CVE
CVE-2021-25641
Published
May 29, 2021
Updated
Aug 3, 2024
Vendor
The Apache Software Foundation
Product
Apache Dubbo
Classifications
CWE-502, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 29, 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=Apache Dubbo 2.6.x <2.6.9
  2. Affected versionversion=Apache Dubbo 2.7.x <2.7.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Dubboversion=Apache Dubbo 2.6.x <2.6.9; version=Apache Dubbo 2.7.x <2.7.8

Published CVSS scores

9.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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.

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 exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1210Exploitation of Remote Services

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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