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PillowApplication · Python

CVE-2021-34552

CRITICAL · 9.8 CVSS v3.1 Published 2021-07-13
Fix available
A fix is available. Upgrade to after 8.2.0 or later.
See remediation →
100/100
Remediation priority · Urgent
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
Pillow through 8.2.0 and PIL (aka Python Imaging Library) through 1.1.7 allow an attacker to pass controlled parameters directly into a convert function to trigger a buffer overflow in Convert.c.

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

A buffer overflow vulnerability exists in Pillow through 8.2.0 and PIL through 1.1.7 in the Convert.c file. An attacker can trigger this by passing specially crafted, controlled parameters directly to a convert function, causing memory corruption and potential arbitrary code execution.

MitigationUpdate Pillow to version 8.3.0 or later and PIL to version 1.1.7post1 or later to obtain the patched Convert.c code with proper bounds checking in the convert function.

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
PillowApplication
Affected:>= 1.0, <= 1.1.7>= 1.2, <= 8.2.0
Debian LinuxOperating system
Affected:= 9.0
FedoraOperating system
Affected:= 33= 34

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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. Check installed Pillow version
    Run 'python -c "import PIL; print(PIL.__version__)"' or 'pip show pillow' to see the installed Pillow version
    Affected if The version is 8.2.0 or lower, or 1.1.7 or lower (any version <= 8.2.0 from the >=1.0, <=8.2.0 range is affected)
  2. Check installed PIL version
    Run 'python -c "import PIL; print(PIL.__version__)"' (note: older PIL package may show version differently) or check pip list for 'PIL' or 'Pillow' packages
    Affected if The version is 1.1.7 or lower (PIL is affected from >=1.0 through <=1.1.7)
  3. Check Debian 9.0 system package
    Run 'dpkg -l | grep -i pillow' or 'apt show python-pil' to check the installed package version on Debian
    Affected if The installed pillow or python-pil package version matches Debian 9.0 and is unpatched
  4. Check Fedora system package
    Run 'rpm -qa | grep -i pillow' to check the installed Pillow package version on Fedora 33 or 34
    Affected if The installed pillow package matches Fedora 33 or 34 and is unpatched
  5. Identify convert function usage
    Search your codebase for direct calls to PIL's convert function (e.g., 'image.convert()') with parameters that could be attacker-controlled, particularly in contexts where images are processed from untrusted sources
    Affected if Your code passes user-supplied or network-supplied arguments directly to any convert() method without validation

You are affected if your installed Pillow version is 8.2.0 or lower, or your PIL version is 1.1.7 or lower, and you use the convert function with external 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.

dbcve · scoped
Upgrade available Upgrade to a release after 8.2.0
Interim mitigation

Update Pillow to version 8.3.0 or later and PIL to version 1.1.7post1 or later to obtain the patched Convert.c code with proper bounds checking in the convert function.

Recommended fix High confidence

Pillow >= 8.3.0 (latest stable release recommended)

  1. Check the current installed version of Pillow using: pip show pillow or pip list | grep -i pillow
  2. Upgrade Pillow to the latest stable release to receive the security fix: pip install --upgrade Pillow
  3. Verify the upgrade was successful and the new version is >= 8.3.0: pip show pillow
  4. If using a system package manager (apt, dnf, etc.), update the system package for Pillow to the latest available version
Caveat Upgrading major versions may introduce breaking changes; review Pillow changelog if upgrading across major version boundaries

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Pillow Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
18.0 hours of engineering $3,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,864.

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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-2021-34552 in production — separate from our analysis above.

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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