vulnerability / NVI-00010743 / Revision 2
Pillow: Infinite loop in PdfParser.rewrite_pages on page tree Parent cycle
GitHub lists this reviewed advisory for Pillow. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
0.573%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.47354. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
Pillow
source listed>= 5.1.0, < 13.0.0
``` ============================================================================ Infinite loop in PdfParser.rewrite_pages on page tree Parent cycle Location: src/PIL/PdfParser.py:505 in PdfParser.rewrite_pages() Commit: a707c6b21c313880d0771e54965d142dd42358b6 ============================================================================ ``` A PDF file of a few hundred bytes makes Pillow hang forever, holding one processor core at 100%, when an application tries to append an image to it. Anyone who can supply the existing PDF to an application that calls `im.save(fp, "PDF", append=True)` (or `save_all=True, append=True`) can tie up that worker indefinitely. Memory use stays flat, so only an external timeout stops it. The bug is in `PdfParser.rewrite_pages()` in `src/PIL/PdfParser.py` (the `while pages_tree_node_ref:` loop at line 505). For each original page, it walks the `/Parent` chain upward and stops only when it reaches a node with no `/Parent`. It keeps no record of nodes it has already visited, so a loop in that chain never ends. The simplest case is a `/Pages` root that lists itself as its own `/Parent`; a longer cycle among page-tree nodes behaves the same way. The path
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-f2g6-542v-9j58 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-112406 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.