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CVE-2026-113793

pypdf: Possible infinite loop when removing tree items

6.0 MediumFix available

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.35%Down 0.1 points since Oct 22, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.0

pypdf: Possible infinite loop when removing tree items

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.

Record
CVE-2026-113793
CVSS 4.0
6.0 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-02
EUVDEUVD-2026-107334 6.0

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.

Record
EUVD-2026-107334
CVSS 4.0
6.0 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-9mx8-4j7g-633p 6.0

pypdf: Possible infinite loop when removing tree items

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires removing an object from a tree, for example an outline item.

Patches

This has been fixed in pypdf==6.20.1.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4188.

Record
GHSA-9mx8-4j7g-633p
CVSS 4.0
6.0 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-02
NVD 6.0

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.

Record
CVE-2026-113793
CVSS 4.0
6.0 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/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
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Weakness
CWE-835
Updated
2026-11-05
OSV 6.0

pypdf: Possible infinite loop when removing tree items

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.

Record
CVE-2026-113793
CVSS 4.0
6.0 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-07
OSVDEBIAN-CVE-2026-113793 4.3

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.

Record
DEBIAN-CVE-2026-113793
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Updated
2026-11-06
Show 4 moreShow less
OSVGHSA-9mx8-4j7g-633p 6.0

pypdf: Possible infinite loop when removing tree items

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires removing an object from a tree, for example an outline item.

Patches

This has been fixed in pypdf==6.20.1.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4188.

Record
GHSA-9mx8-4j7g-633p
CVSS 4.0
6.0 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-02
OSVUBUNTU-CVE-2026-113793 6.0

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.

Record
UBUNTU-CVE-2026-113793
CVSS 4.0
6.0 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Updated
2026-11-07
OSVCLSA-2026-1793019428 No score

TuxCare security update for pypdf (5 CVEs)

TuxCare rebuilt pypdf to address 5 CVEs. Fixed in 5.9.0.post21+tuxcare.

Record
CLSA-2026-1793019428
Updated
2026-11-02
OSVopenSUSE-SU-2026:22188-1 No score

Security update for python-pypdf

This update for python-pypdf fixes the following issues:

Changes in python-pypdf:

  • CVE-2026-113786: PDF containing image data labeled with the /DCTDecode filter causes Pillow to select and invoke an unintended image parser when the image is loaded (bsc#1286632)
  • CVE-2026-113789: crafted PDF causes large memory usage or long runtimes when an application retrieves the document's form fields (bsc#1286633)
  • CVE-2026-113790: PDF containing arrays or dictionaries with many elements causes parsing to consume large amounts of memory (bsc#1286634)
  • CVE-2026-113791: PDF containing a content stream with many small operations causes parsing to consume large amounts of memory (bsc#1286635)
  • CVE-2026-113792: calling PdfWriter.find_outline_item on a crafted PDF with a cyclic outline hierarchy can enter an infinite loop and block the current process (bsc#1286636)
  • CVE-2026-113793: removing an object from a crafted cyclic PDF tree can enter an infinite loop and block the current process (bsc#1286637)
  • CVE-2026-113794: incomplete PDF that ends inside a standard cross-reference table causes pypdf to mishandle the unexpected end of file and enter an infinite loop (bsc#1286638)
  • CVE-2026-113795: accessing a crafted PDF stream with a large number of filters or multiple filters that pass around large amounts of data can cause large memory consumption (bsc#1286639)
Record
openSUSE-SU-2026:22188-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
pypdf
PyPI
 before 6.20.1
6.20.1
pypdf
TuxCare:PyPI
From an advisory covering 5 CVEs
 5.9.0 up to 5.9.0.post21+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 15 moreShow less
5.9.0.post14+tuxcare5.9.0.post15+tuxcare5.9.0.post16+tuxcare5.9.0.post17+tuxcare5.9.0.post18+tuxcare5.9.0.post19+tuxcare5.9.0.post2+tuxcare5.9.0.post20+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.post21+tuxcare
pypdf
Debian: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 less
4.0.1-14.0.2-14.1.0-14.2.0-14.3.1-15.4.0-16.19.0-16.21.0-16.21.1-16.21.4-16.9.0-16.9.2-16.9.2-2
 None known
pypdf
Debian: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
pypdf
Debian:14
 before 6.21.0-1, plus listed versions
5.4.0-16.19.0-16.9.0-16.9.2-16.9.2-2
6.21.0-1
pypdf2
Debian:12
 All versions, plus listed versions
2.12.1-32.12.1-3+deb12u12.12.1-4
 None known
pypdf
PyPI
 before 6.20.1, plus listed versions
1.01.11.101.111.12
Show 45 moreShow less
1.131.21.31.41.51.61.71.81.93.1.03.10.03.11.03.11.13.12.03.12.13.12.23.13.03.14.03.15.03.15.13.15.23.15.33.15.43.15.53.16.03.16.13.16.23.16.33.16.43.17.03.17.13.17.23.17.33.17.43.2.03.2.13.3.03.4.03.4.13.5.03.5.13.5.23.6.03.7.03.7.1
6.20.1
pypdf2
Ubuntu:Pro:16.04:LTS
 All versions, plus listed versions
1.23+git20141008-11.25.1-11.25.1-1ubuntu0.1~esm11.25.1-1ubuntu0.1~esm2
 None known
pypdf2
Ubuntu:Pro:18.04:LTS
 All versions, plus listed versions
1.26.0-21.26.0-2ubuntu0.1~esm11.26.0-2ubuntu0.1~esm2
 None known
pypdf2
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.26.0-21.26.0-3ubuntu11.26.0-3ubuntu1.20.04.11.26.0-3ubuntu1.20.04.2
 None known
Show 6 moreShow less
Affected packages
PackageAffectedFixed
pypdf2
Ubuntu:22.04:LTS
 All versions, plus listed versions
1.26.0-41.26.0-4ubuntu0.22.04.11.26.0-4ubuntu0.22.04.2
 None known
pypdf
Ubuntu: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
pypdf2
Ubuntu:24.04:LTS
 All versions, plus listed versions
2.12.1-32.12.1-4
 None known
pypdf
Ubuntu:26.10
 All versions, plus listed versions
6.9.2-16.9.2-2
 None known
pypdf
Ubuntu:26.04:LTS
 All versions, plus listed versions
5.4.0-16.9.2-1
 None known
python-pypdf
openSUSE:Leap 16.0
From an advisory covering 8 CVEs
 before 6.19.0-bp160.2.1
6.19.0-bp160.2.1

History

History
RecordedChangedSources
affectedOSV
affected
facts, referencesNVD
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-113793 is a medium vulnerability (CVSS 6.0) in Py-pdf Pypdf, published October 21, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 29th percentile. Fixed in pypdf 6.20.1.

References

Show 21 moreShow less
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Left out here: 71 versions. The JSON record has them.

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