Ecosyste.ms: Advisories

Security Advisories: GSA_kwCzR0hTQS1obTl2LXZqM3ItcjU1bc4AA0Ka

PyPDF2 vulnerable to possible Infinite Loop when reading malformed objects

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:

    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

    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
• pypdf PR #1331

Permalink: https://github.com/advisories/GHSA-hm9v-vj3r-r55m
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS1obTl2LXZqM3ItcjU1bc4AA0Ka
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: 10 months ago
Updated: 6 months ago

CVSS Score: 6.2
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Identifiers: GHSA-hm9v-vj3r-r55m, CVE-2023-36807
References:

• 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

Repository: https://github.com/py-pdf/pypdf
Blast Radius: 19.9

Affected Packages