CVE-2021-25640Network attack vector

SSRF and open redirect via host-check bypass

Published May 31, 2021 · Updated Aug 3, 2024

SSRF and open redirect in Apache Dubbo before 2.6.9 and 2.7.9 allow remote attackers to route URLs to unapproved hosts. The parseURL method accepts a crafted URL in a form that bypasses the host allowlist, allowing an unapproved destination to be used. Exploitation requires user interaction and can redirect a request or make the server contact an attacker-selected host; availability is not affected.

CVSS severity6.1
Medium
EPSS probability2.07%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF and open redirect in Apache Dubbo before 2.6.9 and 2.7.9 allow remote attackers to route URLs to unapproved hosts. The parseURL method accepts a crafted URL in a form that bypasses the host allowlist, allowing an unapproved destination to be used. Exploitation requires user interaction and can redirect a request or make the server contact an attacker-selected host; availability is not affected.

The record

CVE
CVE-2021-25640
Published
May 31, 2021
Updated
Aug 3, 2024
Vendor
The Apache Software Foundation
Product
Apache Dubbo
Classifications
CWE-601, CWE-918
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 31, 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 <2.7.9

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 <2.7.9

Published CVSS scores

5.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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-601URL Redirection to Untrusted Site ('Open Redirect')
CWE-918Server-Side Request Forgery (SSRF)

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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