CVE-2026-33123
pypdf has inefficient decoding of array-based streams
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
pypdf has inefficient decoding of array-based streams
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
- Record
CVE-2026-33123- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Weakness
- CWE-400, CWE-407
- Updated
- 2026-11-02
EUVDEUVD-2026-13651
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
- Record
EUVD-2026-13651- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-qpxp-75px-xjcp
pypdf has inefficient decoding of array-based streams
Impact
An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries.
Patches
This has been fixed in pypdf==6.9.1.
Workarounds
If you cannot upgrade yet, consider applying the changes from PR #3686.
- Record
GHSA-qpxp-75px-xjcp- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Weakness
- CWE-400, CWE-407
- Updated
- 2026-11-02
NVD
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
- Record
CVE-2026-33123- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/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 - CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Weakness
- CWE-400, CWE-407
- Updated
- 2026-11-02
OSV
pypdf has inefficient decoding of array-based streams
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
- Record
CVE-2026-33123- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Weakness
- CWE-400, CWE-407
- Updated
- 2026-11-04
OSVDEBIAN-CVE-2026-33123
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
- Record
DEBIAN-CVE-2026-33123- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
Show 8 moreShow less
OSVGHSA-qpxp-75px-xjcp
pypdf has inefficient decoding of array-based streams
Impact
An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries.
Patches
This has been fixed in pypdf==6.9.1.
Workarounds
If you cannot upgrade yet, consider applying the changes from PR #3686.
- Record
GHSA-qpxp-75px-xjcp- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Weakness
- CWE-400, CWE-407
- Updated
- 2026-11-02
OSVPYSEC-2026-3023
pypdf has inefficient decoding of array-based streams
Impact
An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries.
Patches
This has been fixed in pypdf==6.9.1.
Workarounds
If you cannot upgrade yet, consider applying the changes from PR #3686.
- Record
PYSEC-2026-3023- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-33123
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
- Record
UBUNTU-CVE-2026-33123- CVSS 4.0
- 5.1 Medium
CVSS: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 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVCLSA-2026-1789369936 No score
TuxCare security update for pypdf (8 CVEs)
TuxCare rebuilt pypdf to address 8 CVEs. Fixed in 5.9.0.post17+tuxcare.
- Record
CLSA-2026-1789369936- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:10402-1 No score
python311-PyPDF2-2.11.1-8.1 on GA media
These are all security issues fixed in the python311-PyPDF2-2.11.1-8.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:10402-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:10403-1 No score
python311-pypdf-6.9.1-1.1 on GA media
These are all security issues fixed in the python311-pypdf-6.9.1-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:10403-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:20430-1 No score
Security update for python-PyPDF2
This update for python-PyPDF2 fixes the following issues:
Changes in python-PyPDF2:
- CVE-2026-33123: Fixed excessive resource consumption when processing specially crafted PDF due to inefficient decoding of array-based streams (bsc#1259992)
- Record
openSUSE-SU-2026:20430-1- Updated
- 2026-11-02
OSVROOT-APP-PYPI-CVE-2026-33123 No score
CVE-2026-33123 in pypdf - Patched by Root
Root has patched CVE-2026-33123 in the pypdf package for Root:PyPI. Multiple fixed versions available.
- Record
ROOT-APP-PYPI-CVE-2026-33123- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
pypdfPyPI |
before 6.9.1 | 6.9.1 |
pypdfTuxCare:PyPI From an advisory covering 7 CVEs |
5.9.0 up to 5.9.0.post17+tuxcare, plus listed versions 5.9.0.post1+tuxcare5.9.0.post10+tuxcare5.9.0.post11+tuxcare5.9.0.post12+tuxcare5.9.0.post13+tuxcare Show 11 moreShow less5.9.0.post14+tuxcare5.9.0.post15+tuxcare5.9.0.post16+tuxcare5.9.0.post2+tuxcare5.9.0.post3+tuxcare5.9.0.post4+tuxcare5.9.0.post5+tuxcare5.9.0.post6+tuxcare5.9.0.post7+tuxcare5.9.0.post8+tuxcare5.9.0.post9+tuxcare |
5.9.0.post17+tuxcare |
pypdfDebian:12 |
All versions, plus listed versions 3.17.4-13.4.1-13.4.1-1+deb12u14.0.0-14.0.0-1~exp1 Show 13 moreShow less4.0.1-14.0.2-14.1.0-14.2.0-14.3.1-15.4.0-16.19.0-16.21.0-16.21.1-16.21.4-16.9.0-16.9.2-16.9.2-2 |
None known |
pypdfDebian:13 |
All versions, plus listed versions 5.4.0-16.19.0-16.21.0-16.21.1-16.21.4-16.9.0-16.9.2-16.9.2-2 |
None known |
pypdfDebian:14 |
before 6.9.2-1, plus listed versions 5.4.0-16.9.0-1 |
6.9.2-1 |
pypdf2Debian:12 |
All versions, plus listed versions 2.12.1-32.12.1-3+deb12u12.12.1-4 |
None known |
pypdfPyPI |
before 6.9.1, plus listed versions 1.01.11.101.111.12 Show 45 moreShow less1.131.21.31.41.51.61.71.81.93.1.03.10.03.11.03.11.13.12.03.12.13.12.23.13.03.14.03.15.03.15.13.15.23.15.33.15.43.15.53.16.03.16.13.16.23.16.33.16.43.17.03.17.13.17.23.17.33.17.43.2.03.2.13.3.03.4.03.4.13.5.03.5.13.5.23.6.03.7.03.7.1 |
6.9.1 |
pypdfRoot:PyPI |
before 6.6.0+aikido.7 | 6.6.0+aikido.76.6.0+aikido.86.6.0+aikido.96.6.0+aikido.106.6.0+aikido.116.6.0+aikido.126.6.0+aikido.136.6.0+aikido.146.6.0+aikido.15 |
rootio-pypdfRoot:PyPI |
before 6.6.0+root.io.5 | 6.6.0+root.io.56.6.0+root.io.66.6.0+root.io.76.6.0+root.io.86.6.0+root.io.96.6.0+root.io.106.6.0+root.io.11 |
pypdfUbuntu:24.04:LTS |
All versions, plus listed versions 3.4.1-13.17.4-14.0.0-14.0.1-14.0.2-1 |
None known |
Show 5 moreShow less
| Package | Affected | Fixed |
|---|---|---|
pypdfUbuntu:25.10 |
All versions, plus listed versions 4.3.1-15.4.0-1 |
None known |
pypdfUbuntu:26.10 |
All versions, plus listed versions 6.9.2-16.9.2-2 |
None known |
pypdfUbuntu:26.04:LTS |
All versions, plus listed versions 5.4.0-16.9.2-1 |
None known |
python-PyPDF2openSUSE:Tumbleweed |
before 2.11.1-8.1 | 2.11.1-8.1 |
python-pypdfopenSUSE:Tumbleweed |
before 6.9.1-1.1 | 6.9.1-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| facts | OSV | |
| affected | OSV | |
| affected | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-33123 is a medium vulnerability (CVSS 5.1) in Py-pdf Pypdf, published March 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.36%, the 30th percentile. Fixed in pypdf 6.9.1.
References
Left out here: 46 versions. The JSON record has them.