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Commons EmailApplication · Apache

CVE-2017-9801

HIGH · 7.5 CVSS v3.0 Published 2017-08-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
When a call-site passes a subject for an email that contains line-breaks in Apache Commons Email 1.0 through 1.4, the caller can add arbitrary SMTP headers.

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 confidence

Apache Commons Email versions 1.0 through 1.4 are vulnerable to SMTP header injection. When line-break characters are present in the email subject parameter, attackers can inject arbitrary SMTP headers (such as CC, BCC, or additional From addresses) by embedding newline characters in the subject field, allowing email spoofing or unauthorized message routing.

MitigationUpgrade Apache Commons Email to version 1.5 or later which properly sanitizes input and rejects line breaks in the subject field. Additionally, implement input validation to strip or reject newline characters from all user-supplied email parameters before passing them to the library.

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
Commons EmailApplication
Affected:= 1.0= 1.1= 1.2= 1.3= 1.3.1= 1.3.2= 1.3.3= 1.4

CVSS 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
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Locate Apache Commons Email library
    Search for commons-email*.jar files in your application lib directories, or check your build configuration (pom.xml for Maven, build.gradle for Gradle) for the commons-email dependency
    Affected if The library is present in your environment
  2. Determine installed version
    Inspect the JAR file name or check the MANIFEST.MF file inside the JAR for the Version attribute, or look at the dependency declaration in your build file
    Affected if The version is 1.0, 1.1, 1.2, 1.3, 1.3.1, 1.3.2, 1.3.3, or 1.4
  3. Identify code using email subject parameter
    Search your codebase for calls to setSubject() or withSubject() methods on Email objects, especially where the argument comes from user input, request parameters, or external data sources
    Affected if User-controlled data is passed to the subject parameter without validation
  4. Verify input sanitization for subject field
    Inspect the code handling the subject value before passing it to the Email API; look for validation that strips, rejects, or sanitizes newline characters (\n, \r) or other SMTP special characters
    Affected if No validation exists to remove or reject line-break characters from the subject input before it reaches the library
  5. Test for header injection possibility
    If you have access to test the email functionality, attempt to set the subject with a value containing newline characters followed by additional headers (e.g., 'Subject: Test\nCC: [email protected]') and observe if multiple recipients or headers are accepted
    Affected if The application accepts and processes line breaks in the subject field, allowing header injection

Your environment is affected if Apache Commons Email version 1.0 through 1.4 is in use AND user-supplied input is passed to the email subject parameter without sanitizing line-break characters.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Apache Commons Email to version 1.5 or later which properly sanitizes input and rejects line breaks in the subject field. Additionally, implement input validation to strip or reject newline characters from all user-supplied email parameters before passing them to the library.

Fix this in Commons Email Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-9801 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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