Pillow EUVD-2026-41899

| CVE-2026-54059 HIGH

Memory Allocation with Excessive Size Value (CWE-789)

2026-07-06 GitHub_M

GHSA-8v84-f9pq-wr9x PYSEC-2026-2253

Python Information Disclosure Pillow Python Pillow

7.5

CVSS 3.1 · Vendor: GitHub_M

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Identify service that loads untrusted PCF fonts
Delivery

Submit crafted PCF with oversized METRICS dimensions
Exploit

Pillow reads glyph size, skips bomb check
Execution

Image.frombytes() requests huge allocation
Impact

Memory exhausted, worker/host crashes (DoS)

Vulnerability Assessment

Weakness	CWE CWE-789 ASVS 5.0 V15 - Secure Coding and Architecture Memory allocation limits
Exploitation Conditions	Exploitation requires the target application to load an attacker-controlled PCF (X11 Portable Compiled Format) bitmap font through Pillow's PcfFontFile loader - for example via ImageFont/PcfFontFile on an uploaded or fetched .pcf file. The concrete prerequisite is that untrusted PCF font data reaches _load_bitmaps(); applications that never parse external PCF fonts are not exposed. Limiting factors: only the PCF code path is affected (not JPEG/PNG/other formats), the impact is confined to memory-exhaustion denial of service with no code execution or data disclosure, and reachability depends on the application deliberately accepting third-party fonts. No authentication is required at the CVSS level (PR:N), but the practical attack surface is narrowed to font-processing features.
Impact	The NVD CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, base 7.5) rates this High, driven entirely by the availability impact - confidentiality and integrity are explicitly N, so despite the 'Information Disclosure' tag this is a denial-of-service issue, a conflict worth flagging. The AV:N/PR:N/UI:N metrics assume the crafted PCF font can reach the parser without authentication or user interaction, which is only true for applications that accept and load untrusted PCF font files; in practice PCF font loading is an uncommon, application-specific path, which tempers real-world exposure. No EPSS score, SSVC decision, KEV listing, or POC was provided, so there is no evidence of active or automatable exploitation - this reads as a genuine but bounded DoS bug that merits routine patching rather than emergency response, unless the deployment specifically ingests attacker-supplied fonts.
Exploit ScenarioDerived	An attacker uploads a maliciously crafted PCF font file to a web service that uses Pillow to render text or preview fonts; when the service calls PcfFontFile to load the glyphs, the inflated METRICS dimensions trigger a massive Image.frombytes() allocation that exhausts memory and crashes the worker or host. Because the flaw is network-reachable (AV:N) with low complexity and no authentication or user interaction required in such a pipeline, repeated submissions can produce sustained denial of service. No public POC has been identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 06, 2026

Uncontrolled memory allocation in the Python Pillow imaging library (all versions prior to 12.3.0) allows a crafted PCF bitmap font to exhaust process memory and crash the host application. The PcfFontFile bitmap loader trusts attacker-supplied glyph dimensions from the font's METRICS section and hands them straight to Image.frombytes() while skipping Pillow's decompression-bomb guard. There is no public exploit identified at time of analysis and it is not listed in CISA KEV; the flaw is an availability-only denial of service (CVSS 7.5), not the information disclosure implied by the source tag.

RemediationAI

Upgrade to Pillow 12.3.0 or later, which adds the missing Image._decompression_bomb_check() call to _load_bitmaps() (fix commit 0a263e6264aa5399988d9acd3bbfbca2ca3ec77d). This is a vendor-released patch: version 12.3.0. If an immediate upgrade is not possible, avoid loading untrusted or user-supplied PCF font files, or restrict font loading to a vetted allowlist of trusted fonts, since the vulnerable path is only reachable through PCF parsing; where feasible, run image/font processing in a memory-limited sandbox (e.g., cgroup/ulimit-bounded worker) so an oversized allocation kills only the worker rather than the whole service - the trade-off being added operational complexity and potential loss of throughput. Consult GHSA-8v84-f9pq-wr9x and the 12.3.0 release notes for details.

Affected VersionsENISA

Pillow < 12.3.0

Affected Packages

pypi pillow fix: 12.3.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in pypi

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Technical ContextAI · show details

Pillow is the de facto Python imaging library used for decoding, manipulating and rendering images and fonts. The defect is in PIL/PcfFontFile.py, which parses X11 PCF (Portable Compiled Format) bitmap fonts. In _load_bitmaps(), glyph width/height values are read from the font's METRICS section and passed directly to Image.frombytes() without first invoking Image._decompression_bomb_check(), the safeguard Pillow normally uses to reject implausibly large image dimensions. The root cause maps to CWE-789 (Memory Allocation with Excessive Size Value): a size field controlled by untrusted input drives an unbounded allocation. Because the dimensions come from the font file rather than a validated source, a single crafted PCF file can request an allocation far larger than any legitimate glyph.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (GitHub_M) PRIMARY 7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

vuln.today AI 7.5 HIGH

Untrusted PCF font data can arrive over the network with no auth or interaction, but impact is memory-exhaustion DoS only, so C/I:N and A:H.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SUSE HIGH

Red Hat 7.5 HIGH

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

1

Patch available

Jul 06, 2026 - 20:02 EUVD

DescriptionCVE.org

Pillow is a Python imaging library. Prior to 12.3.0, PIL/PcfFontFile.py _load_bitmaps() read glyph dimensions from the PCF METRICS section and passed them directly to Image.frombytes() without calling Image._decompression_bomb_check(), allowing crafted PCF font data to cause excessive memory allocation. This issue is fixed in version 12.3.0.

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

2,739 pypi packages depend on pillow (1,116 direct, 1,651 indirect)

Ecosystem-wide dependent count for version 12.3.0.

Articles & Coverage 1

News 9 New Python Vulnerabilities - 2 Critical, 7 High, 2 With POC Jul 07, 2026

Executive ViewAI

Why It Matters

Python Pillow, a critical image processing library used across enterprise systems, contains a high-severity denial-of-service vulnerability in its PCF font file handler that allows crafted fonts to exhaust process memory and crash applications. No public exploit code has been identified; however, the vulnerability affects all versions prior to 12.3.0 and directly threatens service availability and business continuity.

Business Impact: High

Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score

0.3%

Top 75% exploitable

Prevalence

High

Pillow is one of the most widely used Python imaging libraries

Threat Intel

1

1 sources

Exploit

POC

Public exploit code exists

Data Quality

8 sources

Confidence: High

EUVD

CVE.org

EPSS

Vulnrichment GHSA Vendor

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC Yes

EPSS 0.3%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision

Out-of-Cycle

Exploitation

Poc

System Exposure· derived

Open

Automatable

Yes

Human Impact

High

Technical Impact

Partial

Priority Score

58

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +38

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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Vendor StatusVendor

SUSE

Severity: Important

Product	Status
SUSE Liberty Linux 8	Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP7	Fixed
SUSE Linux Enterprise Server 16.0 SUSE Linux Enterprise Server for SAP applications 16.0	Fixed
openSUSE Leap 16.0	Fixed
openSUSE Tumbleweed	Fixed

References

Advisories & patches

ADVISORY https://access.redhat.com/errata/RHSA-2026:39127 ADVISORY https://github.com/pypa/advisory-database/tree/main/vulns/pillow/PYSEC-2026-2253.yaml ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-54059 ADVISORY https://vuldb.com/vuln/376493 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:22626/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:2875/ REF https://github.com/python-pillow/Pillow/blob/main/docs/releasenotes/12.3.0.rst REF https://github.com/python-pillow/Pillow/commit/0a263e6264aa5399988d9acd3bbfbca2ca3ec77d REF https://github.com/python-pillow/Pillow/security/advisories/GHSA-8v84-f9pq-wr9x

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