CVE-2026-87910

Rejected file extraction via ignored fallback filter result

Published Sep 11, 2026 · Updated Sep 11, 2026

Improper input validation in CPython tarfile before 3.16.0 allows context-dependent attackers to extract a rejected member through link fallback. TarFile link fallback invokes the extraction filter for the replacement member and link location but ignores one None result instead of skipping the member. Exploitation requires processing a crafted archive with a rejecting filter where link creation fails, and the consequence is writing a file that policy excluded.

CVSS severityUnavailable
Unscored
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in CPython tarfile before 3.16.0 allows context-dependent attackers to extract a rejected member through link fallback. TarFile link fallback invokes the extraction filter for the replacement member and link location but ignores one None result instead of skipping the member. Exploitation requires processing a crafted archive with a rejecting filter where link creation fails, and the consequence is writing a file that policy excluded.

The record

CVE
CVE-2026-87910
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
Python Software Foundation
Product
CPython
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 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 <3.16.0

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Python Software Foundation · CPythonversion=0 <3.16.0

Published CVSS scores

No CVSS assessment is available in this record.

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.

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No observations available

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

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

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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