DubboApplication · Apache
CVE-2021-25640
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn Apache Dubbo prior to 2.6.9 and 2.7.9, the usage of parseURL method will lead to the bypass of white host check which can cause open redirect or SSRF vulnerability.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe parseURL method in Apache Dubbo allows bypassing of white host check validation, which can be exploited to perform open redirect attacks (redirecting users to malicious sites) or SSRF (Server-Side Request Forgery) attacks by crafting malicious URLs that circumvent the intended host whitelist protection.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
DubboApplication
>= 2.5.0, < 2.6.9>= 2.7.0, < 2.7.9CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify installed Dubbo versionLocate the Dubbo JAR files or check your dependency management system (Maven pom.xml, Gradle build.gradle, or the dubbo.jar manifest file) to determine the exact version of Apache Dubbo in useAffected if The version is 2.5.0 through 2.6.8, or 2.7.0 through 2.7.8 (these ranges fall within the vulnerable versions)
-
Confirm host whitelist protection is configuredSearch your Dubbo configuration files and code for any host whitelist settings, such as parameters named 'allowedHosts', 'whiteHostList', 'hostWhitelist', or similar, that define permitted hosts for URL validationAffected if A host whitelist is defined but the parseURL method is used to process URLs (the bypass affects any whitelist validation done through this method)
-
Check for HTTP or IIOP protocol exposureExamine your Dubbo service configuration to determine if HTTP (using dubbo://protocol or via Spring/Quarkus REST endpoints) or IIOP protocols are enabled, as these are the typical vectors for crafting malicious URLs to trigger the parseURL bypassAffected if Dubbo exposes HTTP or IIOP endpoints to untrusted networks or users, allowing them to submit crafted URLs
-
Review URL-based routing or gateway configurationsInspect any Dubbo routing rules, API gateway configurations, or service mesh configurations that handle URL-based routing to see if they rely on the parseURL method for host validationAffected if URL routing or gateway components process external URLs through Dubbo's parseURL without additional validation
-
Audit application logs for suspicious redirect or request patternsSearch Dubbo and application logs for unusual outbound HTTP requests, particularly those going to internal infrastructure (127.0.0.1, 169.254.169.254, internal IP ranges) or unexpected external domains, which could indicate exploitation attemptsAffected if Logs show requests to unexpected internal addresses or known malicious domains originating from Dubbo service calls
You are affected if your environment runs a vulnerable Dubbo version (2.5.0-2.6.8 or 2.7.0-2.7.8) and exposes Dubbo HTTP/IIOP endpoints or uses parseURL for host validation on externally-received URLs.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data2.6.92.7.9
Upgrade Apache Dubbo to version 2.6.9, 2.7.9, or later versions where the parseURL method properly validates hosts against the white host list.
Fix this in Dubbo
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-25640 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-25640 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data