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PillowApplication · Python

CVE-2020-35653

HIGH · 7.1 CVSS v3.1 Published 2021-01-12
Fix available
A fix is available. Upgrade to 8.1.0 or later.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges

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
In Pillow before 8.1.0, PcxDecode has a buffer over-read when decoding a crafted PCX file because the user-supplied stride value is trusted for buffer calculations.

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

Pillow's PCX image decoder (PcxDecode) contains a buffer over-read vulnerability where the user-supplied stride value from a crafted PCX file is used directly in buffer calculations without validation, allowing an attacker to read memory beyond allocated buffer boundaries.

MitigationUpgrade Pillow to version 8.1.0 or later which includes proper validation of stride values before performing buffer calculations.

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:< 8.1.0
FedoraOperating system
Affected:= 32= 33
Debian LinuxOperating system
Affected:= 9.0

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
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/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. Determine installed Pillow version
    Run `python -c "import PIL; print(PIL.__version__)"` or `pip show pillow` to retrieve the installed version number
    Affected if The version displayed is less than 8.1.0 (for example, 8.0.x, 7.x.x, or earlier)
  2. Identify PCX image file processing
    Search your application codebase, scripts, or processed files for references to .pcx file extensions or PCX-related Pillow functions such as PcxImageFile or PcxDecode
    Affected if Your environment processes or decodes PCX image files using Pillow
  3. Verify direct use of PcxDecode decoder
    Inspect any custom image decoding code for imports or usage of PIL.PcxImageFile, Image.open() on PCX files, or direct calls to the PcxDecode routine
    Affected if Your code explicitly loads or decodes PCX format images using Pillow's decoder
  4. Check system package manager for Pillow
    On Fedora systems run `dnf list installed python3-pillow`; on Debian systems run `dpkg -l python3-pillow` or `apt list --installed python3-pillow`
    Affected if The installed package version from the package manager is below 8.1.0

You are affected if Pillow version is below 8.1.0 AND your environment processes PCX image files using Pillow's decoder.

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 8.1.0 or later
Fixed in 8.1.0
Interim mitigation

Upgrade Pillow to version 8.1.0 or later which includes proper validation of stride values before performing buffer calculations.

Fix this in Pillow Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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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-2020-35653 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