CVE-2026-42310

Application hang via cyclic PDF trailer pointers

Published May 9, 2026 · Updated May 9, 2026

Infinite-loop DoS in Pillow 4.2.0 through 12.1.1 allows local users to hang applications by supplying a malicious PDF. PdfParser recursively follows attacker-controlled Prev pointers in PDF trailers without detecting previously processed cross-reference offsets. The file must be processed by an application using the affected library; the cycle consumes a CPU core indefinitely and leaves that process unresponsive.

CVSS severity5.1
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite-loop DoS in Pillow 4.2.0 through 12.1.1 allows local users to hang applications by supplying a malicious PDF. PdfParser recursively follows attacker-controlled Prev pointers in PDF trailers without detecting previously processed cross-reference offsets. The file must be processed by an application using the affected library; the cycle consumes a CPU core indefinitely and leaves that process unresponsive.

The record

CVE
CVE-2026-42310
Published
May 9, 2026
Updated
May 9, 2026
Vendor
Pillow
Product
Pillow
Classifications
CWE-835, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 9, 2026CVE publishedPublication date reported by the CVE source.
  2. May 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 4.2.0, < 12.2.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Pillow · Pillowversion=>= 4.2.0, < 12.2.0

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.1GitHubCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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