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Pillow CVE-2026-55379

| EUVDEUVD-2026-41902 HIGH
Memory Allocation with Excessive Size Value (CWE-789)
2026-07-06 GitHub_M GHSA-45hq-cxwh-f6vc PYSEC-2026-2255
Authentication Bypass Python Pillow Red Hat Suse
7.5
CVSS 3.1 · Vendor: GitHub_M
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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 font parsing by a network service needs no auth or interaction (AV:N/PR:N/UI:N) and yields only memory-exhaustion DoS, so C:N/I:N/A:H; UI could be R for desktop use.

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
qualitative
Red Hat
7.5 HIGH
qualitative

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

2
Patch available
Jul 06, 2026 - 20:02 EUVD
Analysis Generated
Jul 06, 2026 - 19:38 vuln.today

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 90,002 pypi packages depend on pillow (19,822 direct, 71,639 indirect)

Ecosystem-wide dependent count for version 12.3.0.

DescriptionCVE.org

Pillow is a Python imaging library. Prior to 12.3.0, PIL/BdfFontFile.py bdf_char() read the BBX width and height field from a BDF font file and passed attacker-controlled dimensions to Image.new() without calling Image._decompression_bomb_check(), bypassing Pillow's documented decompression bomb protection and allowing excessive memory allocation. This issue is fixed in version 12.3.0.

Articles & Coverage 1

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

AnalysisAI

Uncontrolled memory allocation in Python Pillow before 12.3.0 lets a crafted BDF font file exhaust available memory and crash the host application. The BdfFontFile parser trusts the attacker-supplied BBX width/height fields and hands them to Image.new() while skipping Pillow's decompression-bomb size check, so a tiny malicious font can request a huge in-memory bitmap. Impact is availability-only (denial of service); there is no public exploit identified at time of analysis and the issue is not in CISA KEV.

Technical ContextAI

Pillow (PIL fork) is one of the most widely used Python imaging libraries and includes readers for many font formats, including the X11/Unix bitmap BDF format via PIL/BdfFontFile.py. The BDF 'BBX' (bounding box) record encodes a glyph's width and height; the bdf_char() routine read these fields and passed them straight to Image.new(), which allocates a raster buffer proportional to width*height. Pillow ships a documented safeguard, Image._decompression_bomb_check(), meant to reject images whose pixel count exceeds MAX_IMAGE_PIXELS, but that check was never invoked on this code path - leaving the allocation unbounded. This maps to CWE-789 (Memory Allocation with Excessive Size Value): a size value derived from untrusted input drives an unconstrained allocation. The single affected package is identified by CPE cpe:2.3:a:python-pillow:pillow:*:*:*:*:*:*:*:*.

RemediationAI

Vendor-released patch: upgrade to Pillow 12.3.0 or later (pip install --upgrade 'Pillow>=12.3.0'), which adds the missing Image._decompression_bomb_check() call to the BDF path - see the fixing commit 0a263e6264aa5399988d9acd3bbfbca2ca3ec77d and advisory GHSA-45hq-cxwh-f6vc. If you cannot upgrade immediately, do not load untrusted or user-supplied BDF font files, and reject or filter BDF uploads at the application layer; you can also lower Image.MAX_IMAGE_PIXELS and wrap font loading in a resource-bounded context (e.g. per-request memory/timeout limits or a sandboxed worker process) so an oversized allocation fails safely rather than exhausting the host. The trade-off of blocking BDF input is loss of legacy bitmap-font support for users who legitimately need it; tightening MAX_IMAGE_PIXELS may also affect handling of legitimately large images processed by the same code.

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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

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CVE-2026-55379 vulnerability details – vuln.today
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