CVE-2026-33155
Published: 20 March 2026
Summary
CVE-2026-33155 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Qluster Deepdiff. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 22.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SC-5 (Denial-of-service Protection) and SC-6 (Resource Availability).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Flaw remediation directly addresses the vulnerability by requiring patching of DeepDiff to version 8.6.2, which fixes the unrestricted constructor arguments in the _RestrictedUnpickler.
Resource availability controls enforce limits on memory allocation to prevent excessive consumption from malicious pickle payloads using whitelisted types like bytes, list, and range.
Denial-of-service protections mitigate the memory exhaustion attack vector enabled by small untrusted pickle payloads forcing over 10 GB allocation.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The CVE describes remote exploitation of a Python library deserialization flaw via malicious pickle input, directly enabling adversaries to trigger application-level resource exhaustion and crash the target process.
NVD Description
DeepDiff is a project focused on Deep Difference and search of any Python data. From version 5.0.0 to before version 8.6.2, the pickle unpickler _RestrictedUnpickler validates which classes can be loaded but does not limit their constructor arguments. A few…
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of the types in SAFE_TO_IMPORT have constructors that allocate memory proportional to their input (builtins.bytes, builtins.list, builtins.range). A 40-byte pickle payload can force 10+ GB of memory, which crashes applications that load delta objects or call pickle_load with untrusted data. This issue has been patched in version 8.6.2.
Deeper analysisAI
CVE-2026-33155 is a denial-of-service vulnerability in the DeepDiff Python library, which focuses on deep difference and search functionality for Python data structures. The issue affects versions from 5.0.0 up to but not including 8.6.2, stemming from the _RestrictedUnpickler component. This unpickler validates allowable classes from the SAFE_TO_IMPORT list but fails to restrict their constructor arguments. Certain whitelisted types, such as builtins.bytes, builtins.list, and builtins.range, allocate memory proportional to their inputs, enabling attackers to trigger excessive memory consumption.
The vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and is linked to CWE-400 (Uncontrolled Resource Consumption) and CWE-770 (Allocation of Resources Without Limits or Throttling). Remote attackers require no privileges or user interaction to exploit it by supplying a malicious 40-byte pickle payload. Applications that load delta objects or invoke pickle_load with untrusted data can be crashed through forced allocation of over 10 GB of memory, leading to denial of service.
The vulnerability has been addressed in DeepDiff version 8.6.2. Official mitigation details are available in the project's GitHub security advisory (GHSA-54jj-px8x-5w5q) and the patching commit (0d07ec21d12b46ef4e489383b363eadc22d990fb), which recommend upgrading to the fixed release and avoiding untrusted pickle data.
Details
- CWE(s)