CVE-2026-54059
Description
A flaw was found in Pillow, a Python imaging library. A remote attacker could exploit this vulnerability by providing specially crafted PCF font data. This data, when processed, can lead to excessive memory allocation because the library does not properly check for decompression bombs. The primary consequence is a Denial of Service (DoS), which could make the affected system or application unavailable.
Statement
A flaw was found in the Python Pillow library. The PcfFontFile._load_bitmaps() method reads glyph dimensions from the PCF METRICS section and passes them directly to Image.frombytes() without calling Image._decompression_bomb_check(). This allows crafted PCF font data to cause excessive memory allocation, leading to a denial of service condition. An attacker could exploit this by providing a specially crafted PCF font file to an application that uses Pillow's font loading functionality.
Mitigation
Do not load PCF fonts from untrusted sources. If PCF font loading is required, validate font file dimensions before passing them to Pillow, or upgrade to Pillow 12.3.0 or later which includes the fix for this vulnerability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Amplification; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
System resources, CPU and memory, can be quickly consumed. This can lead to poor system performance or system crash.
Frequently Asked Questions
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