Ubuntu LinuxOperating system · Canonical
CVE-2018-7537
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 · uneditedAn issue was discovered in Django 2.0 before 2.0.3, 1.11 before 1.11.11, and 1.8 before 1.8.19. If django.utils.text.Truncator's chars() and words() methods were passed the html=True argument, they were extremely slow to evaluate certain inputs due to a catastrophic backtracking vulnerability in a regular expression. The chars() and words() methods are used to implement the truncatechars_html and truncatewords_html template filters, which were thus vulnerable.
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 confidenceDjango's Truncator.chars() and Truncator.words() methods with html=True contain a catastrophic backtracking vulnerability in a regular expression, causing extreme slowdown on certain malicious inputs. This DoS vulnerability affects truncatechars_html and truncatewords_html template filters.
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
Ubuntu LinuxOperating system
= 14.04= 16.04= 17.10
DjangoFramework / library
>= 1.8, < 1.8.19>= 1.11, < 1.11.11>= 2.0, < 2.0.3
Debian LinuxOperating system
= 7.0= 8.0= 9.0CVSS 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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Identify installed Django versionRun 'django-admin --version' or check your requirements.txt/pip freeze output for the django package versionAffected if The version is 1.8.x before 1.8.19, 1.11.x before 1.11.11, or 2.0.x before 2.0.3
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Locate template files using truncatechars_htmlSearch your codebase for 'truncatechars_html' string in template files (.html) or Python files using the filterAffected if This filter is in use and the Django version is within the affected range
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Locate template files using truncatewords_htmlSearch your codebase for 'truncatewords_html' string in template files (.html) or Python files using the filterAffected if This filter is in use and the Django version is within the affected range
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Check for html=True in Truncator usageSearch Python code for direct calls to Truncator().chars() or Truncator().words() with html=True parameterAffected if The html=True parameter is passed, enabling the vulnerable regex path
You are affected if your Django version is in the vulnerable range (1.8.x < 1.8.19, 1.11.x < 1.11.11, or 2.0.x < 2.0.3) AND you use truncatechars_html, truncatewords_html template filters, or call Truncator methods with html=True in your application code.
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 data1.8.191.11.112.0.3
Upgrade Django to version 2.0.3, 1.11.11, or 1.8.19 or later to receive the patched regex. Alternatively, review and replace the vulnerable regex pattern with a non-backtracking alternative.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-7537 — 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-2018-7537 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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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
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