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CVE-2026-27628

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

1.2 LowFix available

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Active

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.40%Up 0.4 points since Feb 25, 2026
90%50%10%1%

What each source reports

CVE List Score used 1.2

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Record
CVE-2026-27628
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Weakness
CWE-835
Updated
2026-11-02
EUVDEUVD-2026-8601 1.2

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Record
EUVD-2026-8601
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Updated
2026-11-02
GitHub AdvisoriesGHSA-2rw7-x74f-jg35 1.2

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file.

Patches

This has been fixed in pypdf==6.7.2.

Workarounds

If users cannot upgrade yet, consider applying the changes from PR #3655.

Record
GHSA-2rw7-x74f-jg35
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Weakness
CWE-835
Updated
2026-11-02
NVD 1.2

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Record
CVE-2026-27628
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/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
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-02
OSV 1.2

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Record
CVE-2026-27628
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Weakness
CWE-835
Updated
2026-11-04
OSVDEBIAN-CVE-2026-27628 7.5

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Record
DEBIAN-CVE-2026-27628
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
Show 7 moreShow less
OSVGHSA-2rw7-x74f-jg35 1.2

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file.

Patches

This has been fixed in pypdf==6.7.2.

Workarounds

If users cannot upgrade yet, consider applying the changes from PR #3655.

Record
GHSA-2rw7-x74f-jg35
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Weakness
CWE-835
Updated
2026-11-02
OSVPYSEC-2026-3005 1.2

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file.

Patches

This has been fixed in pypdf==6.7.2.

Workarounds

If users cannot upgrade yet, consider applying the changes from PR #3655.

Record
PYSEC-2026-3005
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Updated
2026-11-02
OSVUBUNTU-CVE-2026-27628 1.2

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Record
UBUNTU-CVE-2026-27628
CVSS 4.0
1.2 LowCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVCLSA-2026-1778460294 No score

TuxCare security update for pypdf (1 CVE)

TuxCare rebuilt pypdf to address 1 CVE. Fixed in 5.9.0.post4+tuxcare.

Record
CLSA-2026-1778460294
Updated
2026-11-02
OSVopenSUSE-SU-2026:10284-1 No score

python311-PyPDF2-2.11.1-5.1 on GA media

These are all security issues fixed in the python311-PyPDF2-2.11.1-5.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:10284-1
Updated
2026-11-02
OSVopenSUSE-SU-2026:20333-1 No score

Security update for python-PyPDF2

This update for python-PyPDF2 fixes the following issues:

Changes in python-PyPDF2:

  • CVE-2026-27628: Fixed infinite loop when loading circular /Prev entries in cross-reference streams (bsc#1258940)

  • CVE-2026-27888: Fixed issue where manipulated FlateDecode XFA streams can exhaust RAM (bsc#1258934)

  • CVE-2025-55197: Fixed denial of service via craft PDF (bsc#1248089)

  • CVE-2026-27024: Fixed infinite loop when processing TreeObject (bsc#1258691)

  • CVE-2026-27025: Fixed long runtimes/large memory usage for large /ToUnicode streams (bsc#1258692)

  • CVE-2026-27026: Fixed long runtimes for malformed FlateDecode streams (bsc#1258693)

  • Convert to pip-based build

Record
openSUSE-SU-2026:20333-1
Updated
2026-11-02
OSVROOT-APP-PYPI-CVE-2026-27628 No score

CVE-2026-27628 in pypdf - Patched by Root

Root has patched CVE-2026-27628 in the pypdf package for Root:PyPI. Multiple fixed versions available.

Record
ROOT-APP-PYPI-CVE-2026-27628
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
pypdf
PyPI
 before 6.7.2
6.7.2
pypdf
TuxCare:PyPI
 5.9.0 up to 5.9.0.post4+tuxcare, plus listed versions
5.9.0.post1+tuxcare5.9.0.post2+tuxcare5.9.0.post3+tuxcare
5.9.0.post4+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 6.9.0-1, plus listed versions
5.4.0-1
6.9.0-1
pypdf2
Debian:12
 All versions, plus listed versions
2.12.1-32.12.1-3+deb12u12.12.1-4
 None known
pypdf
PyPI
 before 6.7.2, 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
6.7.2
pypdf
Root: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-pypdf
Root:PyPI
 before 6.6.0+root.io.2
6.6.0+root.io.26.6.0+root.io.36.6.0+root.io.46.6.0+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
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
Show 9 moreShow less
Affected packages
PackageAffectedFixed
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
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:25.10
 All versions, plus listed versions
4.3.1-15.4.0-1
 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-PyPDF2
openSUSE:Tumbleweed
From an advisory covering 2 CVEs
 before 2.11.1-5.1
2.11.1-5.1

History

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

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

In short

CVE-2026-27628 is a low vulnerability (CVSS 1.2) in Py-pdf Pypdf, published February 25, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 34th percentile. Fixed in pypdf 6.7.2.

References

Show 18 moreShow less
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Left out here: 40 versions. The JSON record has them.

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