CVE-2026-15310Network attack vector

Memory exhaustion via unbounded ZIP member decompression

Published Aug 25, 2026 · Updated Aug 26, 2026

Uncontrolled resource consumption in CPython before 3.16.0 allows attackers to exhaust memory by opening a crafted ZIP archive. ZipExtFile._read1 passes bzip2, LZMA, and Zstandard data to decompress() without a max_length, so a complete chunk expands before output clipping. The gate is a consuming application opening an attacker-supplied archive, and the bounded consequence is memory exhaustion rather than data access or modification.

CVSS severity2.1
Low
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in CPython before 3.16.0 allows attackers to exhaust memory by opening a crafted ZIP archive. ZipExtFile._read1 passes bzip2, LZMA, and Zstandard data to decompress() without a max_length, so a complete chunk expands before output clipping. The gate is a consuming application opening an attacker-supplied archive, and the bounded consequence is memory exhaustion rather than data access or modification.

The record

CVE
CVE-2026-15310
Published
Aug 25, 2026
Updated
Aug 26, 2026
Vendor
Python Software Foundation
Product
CPython
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.15.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Python Software Foundation · CPythonversion=0 <3.15.0

Published CVSS scores

2.1Python Software FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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