Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop when cloning or duplicating a crafted cyclic DictionaryObject. Clone traversal checked generated destination references rather than the original source references, allowing some source cycles to evade the visited-object check. This issue is fixed in version 6.21.4.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| py-pdf | pypdf | < 6.21.4 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | pypdf | 6.21.4-1 | — |
| Debian 13 | pypdf | No fix yet | — |
| Debian 12 | pypdf +1 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | pypdf | No fix yet | — |
| Ubuntu 26.04 LTS | pypdf | No fix yet | — |
| Ubuntu 24.04 LTS | pypdf | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | python-pypdf | 6.19.0-bp160.3.1 | openSUSE-SU-2026:22219-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | open-webui | 0.12.3-r15 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | pypdf | < 6.21.4 | 6.21.4 | GHSA-mfr5-77xh-9j7h |
Advisories 1
- openSUSE-SU-2026:22219-1 Security update for python-pypdf SUSE / openSUSE Security Updates · Nov 4, 2026