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TI-2026-78992 Aliases CVE-2026-96641GHSA-4rm8-3hmm-39fg

Integer overflow in Pillow font width calculation

Priority MEDIUM 62CWE-190Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
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 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-190 and the CVSS impact.

Summary

Pillow before 13.0.0, a Python imaging library, accumulates PILfont text widths in src/_imaging.c and checks positive glyph advances against INT_MAX but not negative advances against INT_MIN. This integer overflow (CWE-190) can turn a negative result into a large positive width, and a remote attacker with no privileges needs user interaction to trigger it. Applications that use getlength() or getsize() can then suffer logic-integrity errors or excess resource consumption.

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, PILfont text-width accumulation in src/_imaging.c checks positive glyph advances against INT_MAX but does not check negative advances against INT_MIN. Repeating a signed 16-bit advance of -32768 can therefore execute a signed C integer overflow in xsize += dx, producing a large positive width from a negative mathematical result. Applications that use getlength(), getsize(), or derived layout, quota, serialization, or allocation calculations can experience logic-integrity errors or resource consumption, while the high-level mask path commonly retains a decompression-bomb check. 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-4rm8-3hmm-39fg
  • 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-4rm8-3hmm-39fg

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, the fixed version for both python-pillow Pillow and PyPI pillow. RHSA-2026:94738, RHSA-2026:94721, RHSA-2026:94717, RHSA-2026:94715, RHSA-2026:94709 and RHSA-2026:94702 fix Red Hat AI Inference Server 3.5. Red Hat lists Exploit Intelligence with no fix planned, and Lightspeed Core, OpenShift Lightspeed, Red Hat Enterprise Linux 8 and other products as affected without a fix.

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-4rm8-3hmm-39fg 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-2026-96641
  2. 2026-10-22 Alias added: GHSA-4rm8-3hmm-39fg
  3. 2026-10-22 Fix available: PyPI/[email protected] · GHSA-4rm8-3hmm-39fg
  4. 2026-10-22 CVSS score added · GHSA-4rm8-3hmm-39fg
  5. 2026-10-22 Weakness changed · GHSA-4rm8-3hmm-39fg
  6. 2026-10-22 6 new references · GHSA-4rm8-3hmm-39fg
  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. 2026-10-28 CISA SSVC decision points changed
  11. 2026-10-28 Priority changed: LOW → MEDIUM
  12. 2026-11-04 Fix available: RHSA-2026:94717 · Red Hat
  13. 2026-11-04 Fix available: RHSA-2026:94715 · Red Hat
  14. 2026-11-04 Fix available: RHSA-2026:94709 · Red Hat
  15. 2026-11-04 Fix available: RHSA-2026:94738 · Red Hat
  16. 2026-11-04 Fix available: RHSA-2026:94702 · Red Hat
  17. 2026-11-04 Fix available: RHSA-2026:94721 · Red Hat
  18. 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

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