CVE-2023-36807: Infinite Loop when reading malformed objects in pypdf
First published: Fri Jun 30 2023(Updated: )
### Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. ### Patches The issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 ### Workarounds If you cannot update your version of `PyPDF2` (preferably to `pypdf>3.1.0` as PyPDF2 is deprecated), you should modify `PyPDF2/generic/_data_structures.py::read_object`. Replace: ```python else: # number object OR indirect reference peek = stream.read(20) stream.seek(-len(peek), 1) # reset to start if IndirectPattern.match(peek) is not None: return IndirectObject.read_from_stream(stream, pdf) else: return NumberObject.read_from_stream(stream) ``` by ```python elif tok in b"0123456789+-.": # number object OR indirect reference peek = stream.read(20) stream.seek(-len(peek), 1) # reset to start if IndirectPattern.match(peek) is not None: return IndirectObject.read_from_stream(stream, pdf) else: return NumberObject.read_from_stream(stream) else: raise PdfReadError( f"Invalid Elementary Object starting with {tok} @{stream.tell()}" ) ``` ### References * [pypdf issue #1329](https://github.com/py-pdf/pypdf/issues/1329) * [pypdf PR #1331](https://github.com/py-pdf/pypdf/pull/1331)
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Pypdf Project Pypdf | =2.10.5 |
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Reference Links
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-hm9v-vj3r-r55m
- https://nvd.nist.gov/vuln/detail/CVE-2023-36807
- https://github.com/py-pdf/pypdf/issues/1329
- https://github.com/py-pdf/pypdf/pull/1331
- https://github.com/py-pdf/pypdf/commit/e6531a25325e7e0174b6a1ba03b57320b5227f6b
- https://github.com/advisories/GHSA-hm9v-vj3r-r55m (Advisory)
Frequently Asked Questions
What is the impact of CVE-2023-36807?
This vulnerability can cause an infinite loop in a PDF, which can use 100% of a CPU core.
How does CVE-2023-36807 affect the affected software?
The affected software can be blocked by a crafted PDF, causing an infinite loop.
What versions of PyPDF2 are affected by CVE-2023-36807?
PyPDF2 version 2.10.5 is affected by this vulnerability.
How can I fix CVE-2023-36807?
Update to PyPDF2 version 2.10.6 to fix this vulnerability.
Where can I find more information about CVE-2023-36807?
You can find more information about CVE-2023-36807 on the GitHub security advisory page and the NIST vulnerability detail page.
- collector/nvd-index
- collector/nvd-cve
- collector/github-advisory-latest
- alias/GHSA-hm9v-vj3r-r55m
- alias/CVE-2023-36807
- collector/github-advisory
- agent/author
- agent/type
- agent/remedy
- agent/softwarecombine
- agent/references
- collector/mitre-cve
- source/MITRE
- agent/weakness
- agent/last-modified-date
- agent/title
- agent/severity
- agent/description
- agent/first-publish-date
- agent/event
- agent/tags
- agent/trending
- vendor/pypdf project
- canonical/pypdf project pypdf
- version/pypdf project pypdf/2.10.5
- package-manager/pip