SpamassassinApplication · Apache
CVE-2017-15705
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 · uneditedA denial of service vulnerability was identified that exists in Apache SpamAssassin before 3.4.2. The vulnerability arises with certain unclosed tags in emails that cause markup to be handled incorrectly leading to scan timeouts. In Apache SpamAssassin, using HTML::Parser, we setup an object and hook into the begin and end tag event handlers In both cases, the "open" event is immediately followed by a "close" event - even if the tag *does not* close in the HTML being parsed. Because of this, we are missing the "text" event to deal with the object normally. This can cause carefully crafted emails that might take more scan time than expected leading to a Denial of Service. The issue is possibly a bug or design decision in HTML::Parser that specifically impacts the way Apache SpamAssassin uses the module with poorly formed html. The exploit has been seen in the wild but not believed to have been purposefully part of a Denial of Service attempt. We are concerned that there may be attempts to abuse the vulnerability in the future.
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 confidenceApache SpamAssassin before 3.4.2 contains a denial of service vulnerability in its HTML::Parser implementation. When processing HTML emails with certain unclosed tags, the parser's event handling incorrectly triggers a 'close' event immediately after 'open' without processing the intervening 'text' event. This causes the parser to mishandle malformed HTML, resulting in excessive scan times that can timeout the spam scanning process.
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
SpamassassinApplication
< 3.4.2
Ubuntu LinuxOperating system
= 12.04= 14.04= 16.04= 18.04
Debian LinuxOperating system
= 8.0
Enterprise Linux DesktopOperating system
= 7.0
Enterprise Linux EusOperating system
= 7.5
Enterprise Linux ServerOperating system
= 7.0
Enterprise Linux WorkstationOperating system
= 7.0CVSS 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
- None
- Availability
- Low
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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.
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Check SpamAssassin versionRun `spamassassin --version` or `sa-learn --version` to display the installed version numberAffected if Version shown is less than 3.4.2
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Check Debian/Ubuntu package versionRun `dpkg -l | grep spamassassin` or `apt show spamassassin` to inspect the installed package versionAffected if Package version is older than 3.4.2-1 (or equivalent) for your distribution
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Check RHEL package versionRun `rpm -q spamassassin` to query the installed RPM package versionAffected if Package version is older than 3.4.2-1 (or equivalent) for RHEL 7.x
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Confirm parser is in useVerify SpamAssassin is operational and scans HTML emails by checking `/var/log/mail.log` or `/var/log/maillog` for recent spamd or spamassassin activityAffected if SpamAssassin processes emails (the vulnerability triggers during HTML email parsing, no config toggle exists for the parser logic)
You are affected if your installed SpamAssassin version is below 3.4.2, as the HTML::Parser DoS triggers on any HTML email scan.
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 data3.4.2
Upgrade Apache SpamAssassin to version 3.4.2 or later to patch the HTML::Parser event handling logic.
Fix this in Spamassassin
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-15705 — 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-2017-15705 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
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- 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