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CVE-2026-119203

pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer search

7.1 HighFix available

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

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

0.22%Down 0.1 points since Oct 30, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.1

pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer search

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

Record
CVE-2026-119203
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-02
EUVDEUVD-2026-113374 7.1

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

Record
EUVD-2026-113374
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-5849-834g-hvw5 7.1

pypdf has possible infinite loop when hitting EOF in standard xref table during trailer search

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires opening an incomplete file without a trailer.

Patches

This has been fixed in pypdf==6.21.4.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4289.

Record
GHSA-5849-834g-hvw5
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-02
NVD 7.1

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

Record
CVE-2026-119203
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/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
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-02
OSV 7.1

pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer search

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

Record
CVE-2026-119203
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-04
OSVDEBIAN-CVE-2026-119203 5.5

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

Record
DEBIAN-CVE-2026-119203
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-06
Show 4 moreShow less
OSVGHSA-5849-834g-hvw5 7.1

pypdf has possible infinite loop when hitting EOF in standard xref table during trailer search

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires opening an incomplete file without a trailer.

Patches

This has been fixed in pypdf==6.21.4.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4289.

Record
GHSA-5849-834g-hvw5
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/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-2026-119203 7.1

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

Record
UBUNTU-CVE-2026-119203
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-05
OSVCLSA-2026-1793872631 No score

TuxCare security update for pypdf (6 CVEs)

TuxCare rebuilt pypdf to address 6 CVEs. Fixed in 5.9.0.post22+tuxcare.

Record
CLSA-2026-1793872631
Updated
2026-11-05
OSVopenSUSE-SU-2026:22219-1 No score

Security update for python-pypdf

This update for python-pypdf fixes the following issues:

Changes in python-pypdf:

  • CVE-2026-119209: negative /Index values and multiplied xref streams can lead to clamp bypass and server memory exhaustion (bsc#1288950)
  • CVE-2026-119208: trusting forged /Count values in encrypted PDF page trees can lead to excessive resource consumption and denial of service (bsc#1288951)
  • CVE-2026-119207: nested exception text accumulation in strict mode parsing can lead to memory amplification and application denial of service (bsc#1288952)
  • CVE-2026-119206: repeated sequential /Nums scanning in page_labels resolution can lead to algorithmic complexity attacks and denial of service (bsc#1288944)
  • CVE-2026-119205: misdirected reference tracking during dictionary cloning can lead to cycle-detection bypass and thread-hanging infinite loops (bsc#1288943)
  • CVE-2026-119204: unbounded resource entry copying during page-tree flattening can lead to excessive memory allocation and denial of service (bsc#1288942)
  • CVE-2026-119203: unterminated trailer search in incomplete cross-reference tables can lead to an infinite loop and thread-blocking denial of service (bsc#1288941)
Record
openSUSE-SU-2026:22219-1
Updated
2026-11-04

Affected products

Affected packages

Affected packages
PackageAffectedFixed
pypdf
PyPI
 before 6.21.4
6.21.4
pypdf
TuxCare:PyPI
From an advisory covering 6 CVEs
 5.9.0 up to 5.9.0.post22+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 16 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.post21+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.post22+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 6.21.4-1, plus listed versions
5.4.0-16.19.0-16.21.0-16.21.1-16.9.0-16.9.2-16.9.2-2
6.21.4-1
pypdf2
Debian:12
 All versions, plus listed versions
2.12.1-32.12.1-3+deb12u12.12.1-4
 None known
pypdf
PyPI
 before 6.21.4, 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
6.21.4
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
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 7 CVEs
 before 6.19.0-bp160.3.1
6.19.0-bp160.3.1

History

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

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

In short

CVE-2026-119203 is a high vulnerability (CVSS 7.1) in Py-pdf Pypdf, published October 29, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in pypdf 6.21.4.

References

Show 19 moreShow less
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Left out here: 76 versions. The JSON record has them.

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