CVE-2020-11995Public exploitNetwork attack vector

Unauthenticated code execution via Hessian2 HashMap deserialization

Published Jan 11, 2021 · Updated Feb 13, 2025

Deserialization in Apache Dubbo before 2.6.9 and 2.7.0 through 2.7.7 allows remote attackers to execute code via crafted Hessian2 requests. Hessian2 rebuilds attacker-supplied HashMap entries and invokes methods such as EqualsBean.hashCode(), enabling gadget chains to load and run malicious classes. A network-reachable Dubbo service using Hessian2 and a compatible gadget classpath is required; successful exploitation runs code in the service process.

CVSS severity9.8
Critical
EPSS probability5.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deserialization in Apache Dubbo before 2.6.9 and 2.7.0 through 2.7.7 allows remote attackers to execute code via crafted Hessian2 requests. Hessian2 rebuilds attacker-supplied HashMap entries and invokes methods such as EqualsBean.hashCode(), enabling gadget chains to load and run malicious classes. A network-reachable Dubbo service using Hessian2 and a compatible gadget classpath is required; successful exploitation runs code in the service process.

The record

CVE
CVE-2020-11995
Published
Jan 11, 2021
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache Dubbo
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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?

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

  1. Affected versionversion=Apache Dubbo <2.6.9 changes=[{"at":"2.7.8","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Dubboversion=Apache Dubbo <2.6.9 changes=[{"at":"2.7.8","status":"unaffected"}]

Published CVSS scores

9.8GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NISTAV:N/AC:L/Au:N/C:P/I:P/A:P
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.

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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 exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

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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