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CVE

CVE-2025-66019

pypdf's LZWDecode streams be manipulated to exhaust RAM
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CVE

CVE-2025-66019

pypdf's LZWDecode streams be manipulated to exhaust RAM

Impact

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 is a follow up to GHSA-jfx9-29x2-rv3j to align the default limit with the one for zlib.

Patches

This has been fixed in pypdf==6.4.0.

Workarounds

If users cannot upgrade yet, use the line below to overwrite the default in their code:

pypdf.filters.LZW_MAX_OUTPUT_LENGTH = 75_000_000

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
6.6
-
4.0
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
C
H
U
0
-
C
H
U
7.5
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Related Resources

No items found.

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j, https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7, https://nvd.nist.gov/vuln/detail/CVE-2025-66019, https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2, https://github.com/py-pdf/pypdf, https://github.com/py-pdf/pypdf/releases/tag/6.4.0

Severity

7.5

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
7.5
EPSS Probability
0.00066%
EPSS Percentile
0.20642%
Introduced Version
0,6.1.3
Fix Available
6.4.0

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