PillowApplication · Python
CVE-2026-59200
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 · uneditedPillow is a Python imaging library. From 5.1.0 until 12.3.0, PdfParser.PdfStream.decode() in PIL/PdfParser.py calls zlib.decompress() with bufsize set to the PDF stream Length field without bounding the decompressed output size, allowing a crafted FlateDecode PDF stream to exhaust memory from a small file. This issue is fixed in version 12.3.0.
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 confidencePillow's PdfParser.PdfStream.decode() method calls zlib.decompress() with bufsize set to the PDF stream Length field without any bounds checking, allowing a malicious FlateDecode PDF stream to cause excessive memory consumption by decompressing to an arbitrarily large size.
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
>= 5.1.0, < 12.3.0CVSS 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
- High
CVSS:3.1/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 checksWork through these to decide whether this CVE applies to you.
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Identify Pillow installation and versionRun 'pip show pillow' or 'pip list | grep -i pillow' to check if Pillow is installed and what version number is reportedAffected if The installed version is >= 5.1.0 and < 12.3.0
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Check for PdfParser usage in codeSearch codebase for imports or references to 'PdfParser' or 'PdfStream' from the Pillow package, and examine any PDF processing code that uses these classesAffected if Code imports or uses PdfParser.PdfStream from Pillow and processes PDF streams
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Verify PDF input processing from untrusted sourcesInspect application code that handles PDF files, particularly those from external or untrusted sources, to determine if Pillow's PDF parsing is invokedAffected if The application processes PDF files from untrusted sources using Pillow's PdfParser module
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Identify FlateDecode stream processingExamine PDF files being processed to see if they contain FlateDecode streams, which trigger the vulnerable decode() method pathAffected if PDF files containing FlateDecode streams are processed by the vulnerable code path
A user is affected if they run Pillow version 5.1.0 through 12.2.x and use the PdfParser module to process PDF streams with FlateDecode from any source, particularly untrusted PDFs.
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.
dbcve · scoped12.3.0
Upgrade Pillow to version 12.3.0 or later. If upgrade is not immediately possible, restrict or validate PDF input processing to untrusted sources.
12.3.0
- Upgrade Pillow to version 12.3.0 or later using: pip install --upgrade Pillow
- Verify the installed version matches or exceeds 12.3.0: pip show Pillow
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Pillow
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 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 $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-59200 — 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-2026-59200 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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- Version or environment caveats, and links to real fixes
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