CVE-2025-66019 | BDVDB-2026-303136 Detail

py-pdfpypdf

Description#

pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, an attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter. This issue has been patched in version 6.4.0.

Impact#

Per CVSS v4.0: confidentiality impact none, integrity impact none, availability impact high. Attack vector: network.

Weaknesses#

CWE-400 Uncontrolled Resource Consumption
CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

References#

Exploit#

No public exploit known

History#

Version 12025-11-25Record published in the CVE List.
Version 22026-01-20Most recent update recorded in the CVE List.

Published

Published: 2025-11-25
Last modified: 2026-01-20

Vendor information

Vendor: py-pdf
Product: pypdf

All py-pdf vulnerabilities

Score

6.6 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 33.1.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Denial of Service

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
< 6.4.0
Fixed
Not stated

Scoring System

CVSS v4.0

6.6 Medium

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/E:U

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Attack Requirements	None
Privileges Required	None
User Interaction	None
Vulnerable System Confidentiality	None
Vulnerable System Integrity	None
Vulnerable System Availability	High
Subsequent System Confidentiality	None
Subsequent System Integrity	None
Subsequent System Availability	None

CVSS v3.1

Not available

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).