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Vulnerabilities

Security fix · CVE-2026-96637

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-2026-96637. 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
High7.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.37%
Remediation
Version ranges on file
Affected products
PyPI pillow · pip pillow · pypi pillow

## Summary SpiderImagePlugin's seek() bypasses the decompression bomb check, allowing a tiny ( DecompressionBombWarning fires correctly. - BYPASS: Image.open(stack, frame0=1x1) passes; im.seek(1) sets size (100,100) with NO DecompressionBombWarning/Error -> the check is bypassed. Real-world impact: a large frame-1 nsam/nrow (e.g. 40000x40000) causes im.load() to allocate ~6.4 GB (mode F) with the bomb check fully bypassed, from a file under 1 KB. ## Suggested fix Call Image._decompression_bomb_check(self.size) at the end of SpiderImageFile._open() (or in seek() after _open()), mirroring GifImagePlugin / TiffImagePlugin. Optionally validate nsam/nrow are positive and sane in _open(). Credit: Yazan Balawneh - CyStack Security Team [pillow_poc_spider_bomb.py](https://github.com/user-attachments/files/30244916/pillow_poc_spider_bomb.py)

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 pillow0 → 13.0.0
  • pip pillow< 13.0.0
  • pypi pillowversion unspecified

How to fix CVE-2026-96637

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-2026-96637. 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 0 → 13.0.0, < 13.0.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption; CWE-409. 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. Prior to 13.0.0, SpiderImageFile.seek() in src/PIL/SpiderImagePlugin.py reparses a later SPIDER stack frame and replaces self._size without rerunning Image._decompression_bomb_check(). A tiny file can use a safe first frame to pass Image.open() and then declare very large dimensions in a later mode F frame. Loading that frame allocates approximately four bytes p

  2. Oct 22, 2026 · GitHub Advisory Database

    Updated

    ## Summary SpiderImagePlugin's seek() bypasses the decompression bomb check, allowing a tiny ( DecompressionBombWarning fires correctly. - BYPASS: Image.open(stack, frame0=1x1) passes; im.seek(1) sets size (100,100) with NO DecompressionBombWarning/Error -> the check is bypassed. Real-world impact: a large frame-1 nsam/nrow (e.g. 40000x40000) causes im.load() to allocate ~6.4 GB (mode F) with the

  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 SpiderImagePlugin's seek() bypasses the decompression bomb check, allowing a tiny ( DecompressionBombWarning fires correctly. - BYPASS: Image.open(stack, frame0=1x1) passes; im.seek(1) sets size (100,100) with NO DecompressionBombWarning/Error -> the check is bypassed. Real-world impact: a large frame-1 nsam/nrow (e.g. 40000x40000) causes im.load() to allocate ~6.4 GB (mode F) with the

Sources

  • CVE.orgVulnerability recordCVE-2026-96637

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-96637

    30-day exploitation probability 0.37%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-g842-9rc4-69pw

    Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-96637

    SpiderImagePlugin's seek() bypasses the decompression bomb check, allowing a tiny (<1KB) crafted SPIDER stack file to trigger a multi-gigabyte allocation on im.load().

    advisories.gitlab.com
  • NIST NVDVulnerability recordCVE-2026-96637

    Pillow is a Python imaging library. Prior to 13.0.0, SpiderImageFile.seek() in src/PIL/SpiderImagePlugin.py reparses a later SPIDER stack frame and replaces self._size without rerunning Image._decompression_bomb_check(). A tiny file can use a safe first frame to pass Image.open()

    nvd.nist.gov
  • PyPA Advisory DatabasePackage advisoryGHSA-g842-9rc4-69pw

    Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS

    osv.dev
  • Red Hat Security DataVendor advisoryCVE-2026-96637

    pillow: pillow: Denial of Service via decompression bomb bypass in SPIDER images

    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
  • 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