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CVE-2023-36807

Infinite Loop when reading malformed objects in pypdf

MEDIUM
6.5
CVSS Score
Published: June 30, 2023 at 06:38 PM UTC
Updated: June 17, 2026 at 06:07 AM UTC
2 products affected across 2 vendorsPypdfPypdf

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.6%
SSVC
PoC

Description

pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 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. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

x_refsource_MISCExploitIssue TrackingVendor Advisory
Source: [email protected]
https://github.com/py-pdf/pypdf/issues/1329
x_refsource_MISCPatch
Source: [email protected]
https://github.com/py-pdf/pypdf/pull/1331
x_refsource_CONFIRMExploitMitigationPatchVendor Advisory
Source: [email protected]
https://github.com/py-pdf/pypdf/security/advisories/GHSA-hm9v-vj3r-r55m

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-835

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