CVE-2025-8194Public exploitNetwork attack vector

Process hang via unchecked negative archive offset

Published Jul 28, 2025 · Updated Jul 31, 2026

Denial of service in CPython tarfile allows remote attackers to hang extraction or entry enumeration with a crafted tar archive. TarInfo._block accepts a negative byte count from a member size field and rounds it instead of rejecting the invalid offset. Any application that passes an attacker-controlled tar archive to TarFile extraction or member enumeration can enter an infinite loop and deadlock, interrupting that process.

CVSS severity7.5
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in CPython tarfile allows remote attackers to hang extraction or entry enumeration with a crafted tar archive. TarInfo._block accepts a negative byte count from a member size field and rounds it instead of rejecting the invalid offset. Any application that passes an attacker-controlled tar archive to TarFile extraction or member enumeration can enter an infinite loop and deadlock, interrupting that process.

The record

CVE
CVE-2025-8194
Published
Jul 28, 2025
Updated
Jul 31, 2026
Vendor
Python Software Foundation
Product
CPython
Classifications
CWE-835, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 28, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <3.9.24
  2. Affected versionversion=3.10.0 <3.10.19
  3. Affected versionversion=3.11.0 <3.11.14
  4. Affected versionversion=3.12.0 <3.12.12
  5. Affected versionversion=3.13.0 <3.13.6
  6. Affected versionversion=3.14.0a1 <3.14.0rc2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Python Software Foundation · CPythonversion=0 <3.9.24; version=3.10.0 <3.10.19; version=3.11.0 <3.11.14; version=3.12.0 <3.12.12; version=3.13.0 <3.13.6; version=3.14.0a1 <3.14.0rc2

Published CVSS scores

7.5Python Software FoundationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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