CVE-2021-27922Public exploitNetwork attack vector

Service interruption via unchecked ICNS image dimensions

Published Mar 3, 2021 · Updated Aug 15, 2025

Uncontrolled resource consumption in Pillow before 8.1.2 allows remote attackers to interrupt applications through a crafted ICNS image. IcnsImagePlugin.read_png_or_jpeg2000 creates an embedded PNG or JPEG 2000 decoder without applying Pillow's decompression-bomb size check. Exposure requires an application to decode attacker-controlled ICNS files, allowing the resulting allocation to exhaust process memory and interrupt service.

CVSS severity7.5
High
EPSS probability4.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Pillow before 8.1.2 allows remote attackers to interrupt applications through a crafted ICNS image. IcnsImagePlugin.read_png_or_jpeg2000 creates an embedded PNG or JPEG 2000 decoder without applying Pillow's decompression-bomb size check. Exposure requires an application to decode attacker-controlled ICNS files, allowing the resulting allocation to exhaust process memory and interrupt service.

The record

CVE
CVE-2021-27922
Published
Mar 3, 2021
Updated
Aug 15, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:N/I:N/A:P
8.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-20Improper Input Validation
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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