CVE-2025-4435Public exploitNetwork attack vector

Arbitrary file write via ignored extraction rejection

Published Jun 3, 2025 · Updated Jul 31, 2026

Improper validation in CPython tarfile allows remote attackers to write rejected archive members during filtered extraction. TarFile.extract and extractall catch a filter's FilterError at errorlevel=0, log the rejection, and continue with the original member instead of skipping it. Reachability requires an application to extract an untrusted tar archive with a filter while errorlevel is 0; a rejected path can then be written to the filesystem.

CVSS severity7.5
High
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper validation in CPython tarfile allows remote attackers to write rejected archive members during filtered extraction. TarFile.extract and extractall catch a filter's FilterError at errorlevel=0, log the rejection, and continue with the original member instead of skipping it. Reachability requires an application to extract an untrusted tar archive with a filter while errorlevel is 0; a rejected path can then be written to the filesystem.

The record

CVE
CVE-2025-4435
Published
Jun 3, 2025
Updated
Jul 31, 2026
Vendor
Python Software Foundation
Product
CPython
Classifications
CWE-682
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 3, 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 <3.9.23
  2. Affected versionversion=3.10.0 <3.10.18
  3. Affected versionversion=3.11.0 <3.11.13
  4. Affected versionversion=3.12.0 <3.12.11
  5. Affected versionversion=3.13.0 <3.13.4
  6. Affected versionversion=3.14.0a1 <3.14.0b3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Python Software Foundation · CPythonversion=0 <3.9.23; version=3.10.0 <3.10.18; version=3.11.0 <3.11.13; version=3.12.0 <3.12.11; version=3.13.0 <3.13.4; version=3.14.0a1 <3.14.0b3

Published CVSS scores

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

Weakness, pattern, technique

CWE-682Incorrect Calculation

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo