dbcve.org
PillowApplication · Python

CVE-2021-25291

HIGH · 7.5 CVSS v3.1 Published 2021-03-19
Fix available
A fix is available. Upgrade to 8.1.1 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
An issue was discovered in Pillow before 8.1.1. In TiffDecode.c, there is an out-of-bounds read in TiffreadRGBATile via invalid tile boundaries.

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

An out-of-bounds read vulnerability exists in Pillow's TiffDecode.c module within the TiffreadRGBATile function. The vulnerability is triggered when processing specially crafted TIFF images with invalid tile boundaries, potentially allowing attackers to read sensitive memory contents or cause a denial of service.

MitigationUpgrade Pillow to version 8.1.1 or later to resolve the out-of-bounds read vulnerability in TIFF processing.

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:< 8.1.1

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:3.1/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check if Pillow is installed
    Run 'pip show pillow' or 'python -c "import PIL; print(PIL.__version__)"'
    Affected if Pillow is not installed or cannot be imported - not affected
  2. Verify the installed Pillow version
    Compare the installed version number to the affected range: < 8.1.1
    Affected if Installed version is 8.1.0 or lower - potentially affected
  3. Confirm TIFF image processing capability
    Check if PIL.Image can be imported and TIFF support is present by running 'python -c "from PIL import Image; print(Image.plugin_maketypes)" or attempt to open a TIFF file
    Affected if Pillow lacks TIFF decoding capability - not affected; if TIFF support exists, continue to next check
  4. Identify TIFF file processing in your environment
    Search codebase or logs for '.tif' or '.tiff' file handling, or monitor for TiffDecode/TiffreadRGBATile function calls during image processing
    Affected if Your code or system processes TIFF images - potentially affected if version is vulnerable

You are affected only if Pillow version is below 8.1.1 AND your environment processes TIFF images with potentially malicious tile boundaries.

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 8.1.1 or later
Fixed in 8.1.1
Interim mitigation

Upgrade Pillow to version 8.1.1 or later to resolve the out-of-bounds read vulnerability in TIFF processing.

Fix this in Pillow Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

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 locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-25291 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2021-25291 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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