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Vulnerabilities

Security fix · CVE-2026-96643

Pillow is a Python imaging library.

Published Oct 21, 2026 · catalog updated Oct 28, 2026 · Red Hat Red Hat Enterprise Linux

Last checked Oct 31, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-96643. EPSS is 0.37%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.37%
Remediation
Version ranges on file
Affected products
PyPI pillow · pip Pillow · pypi pillow

### Summary A PNG file with a large eXIf chunk full of repeated 6-byte markers makes Pillow's EXIF parser take seconds of CPU instead of milliseconds. The cost grows with the square of the chunk size, so a normal small-photo-sized file is enough to cause real delay. ### Details in strips a marker from the start of the EXIF data like this: Each pass makes a new copy of the remaining data. A real camera writes this marker once, so this is not normally a problem. in puts the raw PNG eXIf chunk straight into with no size limit and no check of its content. PNG text chunks (tEXt, zTXt, iTXt) are capped with and . The eXIf chunk has no such cap. If the eXIf chunk is filled with repeated markers instead of real EXIF data, the strip loop runs once per marker, copying a large buffer each time. This is a classic quadratic time bug. ### Steps to reproduce This builds a small PNG in memory and times on it. No external file needed. Expected output on a fixed version: well under 0.1 seconds, the same as a normal file this size. Actual output on the current code: around 3.5 to 3.7 seconds, for a single 1.8MB file. We checked with a prohis time is spent inside the strip loop itself, not somewhere else. We also checked the growth rate across a few sizes (200KB, 600KB, 1.2MB, 1.8MB) and it matches quadratic growth closely, not linear. A pytest version of this test, using so a test run does not hang if the bug is present, is it fails with . ### Impact - Availability: an attacker who can get one PNG file processed can burn several seconds of CPU per request w A bigger file scales worse, since the cost is quadratic, not linear. - Confidentiality: none. - Integrity: none. - This fires through , , and . is the function Pillow's own docs recommend for auto-rotating user photos, so this can hit normal upload handling code, not just an unusual call.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • PyPI pillow11.0.0 → 13.0.0
  • pip Pillow>= 11.0.0, < 13.0.0
  • pypi pillowversion unspecified

How to fix CVE-2026-96643

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-96643. EPSS is 0.37%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Which versions are affected?

Compare what you have installed with Pillow >= 11.0.0, < 13.0.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-407; CWE-606. EPSS 0.37%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Pillow security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 21, 2026 · NIST NVD

    Detected

    Pillow is a Python imaging library. From 11.0.0 until 13.0.0, Exif.load() in src/PIL/Image.py repeatedly slices the remaining EXIF data while it begins with the six-byte Exif header. src/PIL/PngImagePlugin.py accepts an uncapped PNG eXIf chunk, so a file filled with repeated headers causes a new shrinking copy on every iteration and quadratic CPU work. The condition is reachable through Image.gete

  2. Oct 22, 2026 · GitHub Advisory Database

    Updated

    ### Summary A PNG file with a large eXIf chunk full of repeated 6-byte markers makes Pillow's EXIF parser take seconds of CPU instead of milliseconds. The cost grows with the square of the chunk size, so a normal small-photo-sized file is enough to cause real delay. ### Details in strips a marker from the start of the EXIF data like this: Each pass makes a new copy of the remaining data. A real ca

  3. Oct 28, 2026 · PyPA Advisory Database

    Fix available

    pillow fixed in 13.0.0

  4. Oct 28, 2026 · PyPA Advisory Database

    Fix available

    pillow fixed in 13.0.0

  5. Oct 28, 2026 · PyPA Advisory Database

    Updated

    ### Summary A PNG file with a large eXIf chunk full of repeated 6-byte markers makes Pillow's EXIF parser take seconds of CPU instead of milliseconds. The cost grows with the square of the chunk size, so a normal small-photo-sized file is enough to cause real delay. ### Details in strips a marker from the start of the EXIF data like this: Each pass makes a new copy of the remaining data. A real ca

Sources

  • CVE.orgVulnerability recordCVE-2026-96643

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-96643

    30-day exploitation probability 0.37%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-g4qv-2jxx-769h

    Pillow: PNG eXIf chunk makes EXIF parsing run in quadratic time

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-96643

    A PNG file with a large eXIf chunk full of repeated 6-byte markers makes Pillow's EXIF parser take seconds of CPU instead of milliseconds. The cost grows with the square of the chunk size, so a normal small-photo-sized file is enough to cause real delay.

    advisories.gitlab.com
  • NIST NVDVulnerability recordCVE-2026-96643

    Pillow is a Python imaging library. From 11.0.0 until 13.0.0, Exif.load() in src/PIL/Image.py repeatedly slices the remaining EXIF data while it begins with the six-byte Exif header. src/PIL/PngImagePlugin.py accepts an uncapped PNG eXIf chunk, so a file filled with repeated head

    nvd.nist.gov
  • PyPA Advisory DatabasePackage advisoryGHSA-g4qv-2jxx-769h

    Pillow: PNG eXIf chunk makes EXIF parsing run in quadratic time

    osv.dev
  • PyPA Advisory DatabasePackage advisoryPYSEC-2026-4342

    Pillow is a Python imaging library. From 11.0.0 until 13.0.0, Exif.load() in src/PIL/Image.py repeatedly slices the remaining EXIF data while it begins with the six-byte Exif header. src/PIL/PngImagePlugin.py accepts an uncapped PNG eXIf chunk, so a file filled with repeated head

    osv.dev
  • Red Hat Security DataVendor advisoryCVE-2026-96643

    pillow: pillow: Denial of Service via repeated EXIF headers

    access.redhat.com

References

Freshness

Last verified in this catalog Oct 31, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • PyPA Advisory DatabaseOct 28, 2026
  • PyPA Advisory DatabaseOct 28, 2026
  • FIRST EPSSOct 28, 2026
  • GitLab Advisory DatabaseOct 23, 2026
  • GitHub Advisory DatabaseOct 23, 2026
  • Red Hat Security DataOct 23, 2026
  • CVE.orgOct 22, 2026
  • NIST NVDOct 22, 2026