CVE-2026-59935Network attack vector

Service hang via unterminated inline-image decoding

Published Jul 8, 2026 · Updated Jul 8, 2026

Denial of service in py-pdf pypdf before 6.14.2 allows remote attackers to hang PDF-processing services with a crafted PDF. The ASCII85 and ASCIIHex inline-image decoders accept a nonempty combined buffer when the bulk read returns no bytes, then seek backward and repeat instead of treating end-of-stream as an error. No authentication or user interaction is required once an affected application processes the malformed page content stream; the calling worker hangs without disclosing or modifying data.

CVSS severity8.7
High
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in py-pdf pypdf before 6.14.2 allows remote attackers to hang PDF-processing services with a crafted PDF. The ASCII85 and ASCIIHex inline-image decoders accept a nonempty combined buffer when the bulk read returns no bytes, then seek backward and repeat instead of treating end-of-stream as an error. No authentication or user interaction is required once an affected application processes the malformed page content stream; the calling worker hangs without disclosing or modifying data.

The record

CVE
CVE-2026-59935
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
py-pdf
Product
pypdf
Classifications
CWE-835, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 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=< 6.14.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

py-pdf · pypdfversion=< 6.14.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7GitHub, Inc.CVSS: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 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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