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TI-2026-78993 Aliases CVE-2026-96642GHSA-3j72-p6qg-6xp7

Infinite CPU loop in Pillow TarIO with negative member size

Priority MEDIUM 64CWE-835Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 1 fixed, 11 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-835.

Summary

Pillow before 13.0.0 contains a flaw in the TarIO initializer in src/PIL/TarIO.py, which accepts a negative octal member size. The resulting backward seek returns to the same 512-byte header, so the parser loops forever when the requested member name does not match (CWE-835). An unauthenticated remote attacker can cause a denial of service by getting a user to process a crafted TAR file with an application that calls PIL.TarIO.TarIO directly, consuming a full CPU core.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

Description from the CNA

Pillow is a Python imaging library. Prior to 13.0.0, the TarIO initializer in src/PIL/TarIO.py accepts a negative octal member size and computes a backward seek that returns to the same 512-byte header. When the requested member name does not match, the parser repeatedly reads that header, consumes a full CPU core, and never returns. TarIO is reached only when an application directly uses PIL.TarIO.TarIO rather than the default Image.open() path. This issue is fixed in version 13.0.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00345 28th percentileScored 2026-11-07
Fix Partial Pillow (python-pillow): 13.0.0Pillow (PyPI): 13.0.0Red Hat: 6 advisoriesRed Hat: 1 fixed, 11 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
python-pillowPillowbefore 13.0.013.0.0Patch availableCNA
—Pillow (PyPI)before 13.0.013.0.0Patch availableGHSA-3j72-p6qg-6xp7
  • Pillow Vendorpython-pillow Affected before 13.0.0 Fixed in 13.0.0 Patch available CNA
  • Pillow (PyPI) Vendor— Affected before 13.0.0 Fixed in 13.0.0 Patch available GHSA-3j72-p6qg-6xp7

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:*before 13.0.0Vulnerablepython-pillow
  • cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:* Versions before 13.0.0 Vulnerable ·python-pillow

Remediation

Upgrade Pillow to version 13.0.0 or later. For Red Hat AI Inference Server 3.5, apply RHSA-2026:94738, RHSA-2026:94721, RHSA-2026:94717, RHSA-2026:94715, RHSA-2026:94709 or RHSA-2026:94702. The sources list no fixed version for Exploit Intelligence, Lightspeed Core, OpenShift Lightspeed, Red Hat AI Inference Server, Red Hat Ansible Automation Platform 2 and other products.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

  • Fix · CNA Pillow (python-pillow) Fixed in 13.0.0
  • Fix · GHSA-3j72-p6qg-6xp7 Pillow (PyPI) Fixed in 13.0.0 Advisory →

Red Hat 6 advisories

  • RHSA-2026:94738 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (CUDA)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-cuda-rhel9
  • RHSA-2026:94721 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference Tech Preview 3.5.3 (Gaudi)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-gaudi-rhel9
  • RHSA-2026:94717 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (Spyre)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-spyre-rhel9
Show 3 more Red Hat advisories
  • RHSA-2026:94715 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference Model Optimization Tools 3.5.3 (CUDA)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/model-opt-cuda-rhel9
  • RHSA-2026:94709 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (ROCm)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-rocm-rhel9
  • RHSA-2026:94702 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (CPU)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-cpu-rhel9

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Exploit IntelligenceAffectedNo fix planned: Out of support scope
Lightspeed CoreAffectedNo fix yet: Fix deferred
OpenShift LightspeedAffectedNo fix yet: Fix deferred
Red Hat AI Inference ServerAffectedNo fix yet: Fix deferred
Red Hat Ansible Automation Platform 2AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux AI (RHEL AI) 3AffectedNo fix yet: Fix deferred
Red Hat Lightspeed Services for OCPAffectedNo fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)AffectedNo fix yet: Fix deferred
Red Hat Quay 3AffectedNo fix yet: Fix deferred
Red Hat Satellite 6AffectedNo fix yet: Fix deferred
Red Hat AI Inference Server 3.5Fixed RHSA-2026:94702, RHSA-2026:94709, RHSA-2026:94715, RHSA-2026:94717, RHSA-2026:94721, RHSA-2026:94738

Timeline

  1. 2026-10-21 Threatist record created from CVE-2026-96642
  2. 2026-10-22 Alias added: GHSA-3j72-p6qg-6xp7
  3. 2026-10-22 Fix available: PyPI/[email protected] · GHSA-3j72-p6qg-6xp7
  4. 2026-10-22 CVSS score added · GHSA-3j72-p6qg-6xp7
  5. 2026-10-22 Weakness changed · GHSA-3j72-p6qg-6xp7
  6. 2026-10-22 6 new references · GHSA-3j72-p6qg-6xp7
  7. 2026-10-23 Affected versions changed · Red Hat
  8. 2026-10-23 CVSS score added · Red Hat
  9. 2026-10-23 Priority changed: MEDIUM → LOW
  10. 2026-10-27 CVSS score added · NVD
  11. 2026-10-30 CISA SSVC decision points changed
  12. 2026-10-30 Priority changed: LOW → MEDIUM
  13. 2026-11-04 Fix available: RHSA-2026:94717 · Red Hat
  14. 2026-11-04 Fix available: RHSA-2026:94715 · Red Hat
  15. 2026-11-04 Fix available: RHSA-2026:94709 · Red Hat
  16. 2026-11-04 Fix available: RHSA-2026:94738 · Red Hat
  17. 2026-11-04 Fix available: RHSA-2026:94702 · Red Hat
  18. 2026-11-04 Fix available: RHSA-2026:94721 · Red Hat
  19. 2026-11-04 Fix available: Red Hat AI Inference Server 3.5 · Red Hat

References

Patch 1

Advisory 2

Other 3

  • TI-2026-76627 Out-of-bounds read in Pillow TIFF encoder ColorMap handling CVSS 4.0HIGH 8.8
  • TI-2026-76625 Quadratic-time denial of service in Pillow PDF save_all CVSS 4.0HIGH 8.7
  • TI-2026-76605 NULL pointer dereference in Pillow's Image.merge function CVSS 4.0HIGH 8.7
  • TI-2026-76604 Out-of-bounds read in Pillow TIFF decoding leaks heap memory CVSS 4.0HIGH 8.8
  • TI-2026-76602 Double free in Pillow ImagingScaleAffine on allocation failure CVSS 4.0HIGH 8.7
  • TI-2026-76600 GIF seek in Pillow keeps rejected size, allowing denial of service CVSS 4.0HIGH 8.7
See all 110 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences