vulnerability / NVI-00010672 / Revision 3
Pillow: PNG eXIf chunk makes EXIF parsing run in quadratic time
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.
6.5 MEDIUM (3.1)
nvd@nist.gov severity; no combined Null risk score.
7.1 HIGH (4.0)
security-advisories@github.com severity; no combined Null risk score.
0.373%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.31271. 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>= 11.0.0, < 13.0.0
### Summary A PNG file with a large eXIf chunk full of repeated 6-byte markers makes Pillow's EXIF parser take seconds of CPU instead of milliseconds. The cost grows with the square of the chunk size, so a normal small-photo-sized file is enough to cause real delay. ### Details `Exif.load()` in `src/PIL/Image.py` strips a marker from the start of the EXIF data like this: ```python while data and data.startswith(b"Exif\x00\x00"): data = data[6:] ``` Each pass makes a new copy of the remaining data. A real camera writes this marker once, so this is not normally a problem. `chunk_eXIf()` in `src/PIL/PngImagePlugin.py` puts the raw PNG eXIf chunk straight into `info["exif"]` with no size limit and no check of its content. PNG text chunks (tEXt, zTXt, iTXt) are capped with `MAX_TEXT_CHUNK` and `MAX_TEXT_MEMORY`. The eXIf chunk has no such cap. If the eXIf chunk is filled with repeated `Exif\x00\x00` markers instead of real EXIF data, the strip loop runs once per marker, copying a large buffer each time. This is a classic quadratic time bug. ### Steps to reproduce This builds a small PNG in memory and times `Image.open().getexif()` on it. No external fil
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.
- NVD lastModified does not establish freshness of every associated CPE record.
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-g4qv-2jxx-769h ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-96643 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2026-96643 ↗
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 3 ·
Source facts changed; compare the preserved prior revision.
- 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.