CVE-2026-28351Network attack vector

Memory exhaustion via unbounded RunLengthDecode expansion

Published Feb 27, 2026 · Updated Feb 27, 2026

Uncontrolled resource consumption in pypdf before 6.7.4 allows attackers to exhaust memory by parsing a crafted PDF content stream. RunLengthDecode.decode expands attacker-controlled run records into an in-memory byte list without limiting total decoded output. The application must process a stream using the RunLengthDecode filter; allocation growth can terminate the consuming process or service.

CVSS severity6.9
Medium
EPSS probability0.42%
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 pypdf before 6.7.4 allows attackers to exhaust memory by parsing a crafted PDF content stream. RunLengthDecode.decode expands attacker-controlled run records into an in-memory byte list without limiting total decoded output. The application must process a stream using the RunLengthDecode filter; allocation growth can terminate the consuming process or service.

The record

CVE
CVE-2026-28351
Published
Feb 27, 2026
Updated
Feb 27, 2026
Vendor
py-pdf
Product
pypdf
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 27, 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=< 6.7.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

py-pdf · pypdfversion=< 6.7.4

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
6.9GitHub, Inc.CVSS:4.0/AV:N/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 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-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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