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PythonApplication

CVE-2018-1061

HIGH · 7.5 CVSS v3.0 Published 2018-06-19
Fix available
A fix is available. Upgrade to 2.7.15 / 3.4.9 or later.
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
python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking in the difflib.IS_LINE_JUNK method. An attacker could use this flaw to cause denial of service.

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

Python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 contains a regular expression vulnerability in the difflib.IS_LINE_JUNK method susceptible to catastrophic backtracking, allowing attackers to cause denial of service through specially crafted input.

MitigationUpgrade Python to version 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1, 3.7.0 or later to patch the vulnerability in difflib.IS_LINE_JUNK.

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
PythonApplication
Affected:< 2.7.15>= 3.0, < 3.4.9>= 3.5.0, <= 3.5.5>= 3.6, <= 3.6.4= 3.7.0
Debian LinuxOperating system
Affected:= 8.0= 9.0
Ansible TowerApplication
Affected:= 3.3
Enterprise Linux DesktopOperating system
Affected:= 7.0
Enterprise Linux ServerOperating system
Affected:= 7.0
Enterprise Linux WorkstationOperating system
Affected:= 7.0
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 16.04= 18.04
FedoraOperating system
Affected:= 28= 29= 30

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
None
Availability
High

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

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. Identify installed Python version
    Run 'python --version' or 'python3 --version' in the target environment's shell
    Affected if The version is less than 2.7.15, or between 3.0 and 3.4.8 inclusive, or between 3.5.0 and 3.5.5 inclusive, or between 3.6.0 and 3.6.4 inclusive, or exactly 3.7.0
  2. Locate all Python installations
    Run 'which python' and 'which python3' to find executable paths; check package manager listings (dpkg -l, rpm -qa, apt list) for python packages
    Affected if Any Python installation matches the affected version ranges listed above
  3. Check for difflib usage in deployed code
    Search source code repositories and deployed applications for imports of 'difflib' and references to 'IS_LINE_JUNK' or 'SequenceMatcher' using grep or code scanning tools
    Affected if Code imports and uses difflib with user-supplied input to the IS_LINE_JUNK method
  4. Identify applications using vulnerable Python interpreters
    Review application dependency manifests, container images, virtual environments, and system Python installations to determine which Python versions they ship or reference
    Affected if Applications run on or bundle a Python interpreter matching the affected versions

A system is affected if it runs any Python version less than 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1, or 3.7.1 and executes code that leverages the difflib.IS_LINE_JUNK method with untrusted regular expression input.

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
Upgrade available Upgrade to 2.7.15 / 3.4.9 or later
Fixed in 2.7.153.4.9
Interim mitigation

Upgrade Python to version 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1, 3.7.0 or later to patch the vulnerability in difflib.IS_LINE_JUNK.

Fix this in Python Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2018-1061 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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