pypdf vulnerable to inefficient decoding of ASCIIHexDecode streams (CVE-2026-28804) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-28804GHSA-9M86-7PMV-2852

pypdf vulnerable to inefficient decoding of ASCIIHexDecode streams

Answer in brief

CVE-2026-28804 records a Unknown severity vulnerability in pypdf vulnerable to inefficient decoding of ASCIIHexDecode streams. The current sources do not mark it as known exploited. The current feed maps pypdf (pypi). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Mar 2, 2026Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps pypdf (pypi). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
pypdfpypi	>=0 <6.7.5	6.7.5

Recommended response

Check inventory. Check lockfiles and deployed manifests for pypdf.
Review the reported fix. Update pypdf to 6.7.5 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Mar 2, 2026
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the `/ASCIIHexDecode` filter. ### Patches This has been fixed in [pypdf==6.7.5](https://github.com/py-pdf/pypdf/releases/tag/6.7.5). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3666](https://github.com/py-pdf/pypdf/pull/3666).

Quoted source text, attributed separately from HOL analysis.