GHSA-w476-p2h3-79g9: Uv Uv Has Differential Vulnerability

LOW
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CWE-843
Published
Advisory Summary

GHSA-w476-p2h3-79g9 is a LOW uv has differential vulnerability (CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')) affecting Uv libraries in the PyPI ecosystem. The issue involves uv has differential in tar extraction with pax headers. Remediation is available by upgrading affected packages to version 0.9.5.

GHSA-w476-p2h3-79g9 at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-w476-p2h3-79g9
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')
Affected Product Uv
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix GHSA-w476-p2h3-79g9

To remediate this vulnerability, upgrade all affected Uv dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

uv fixed: 0.9.5 
pip install uv>=0.9.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show uv

How to Check if You Are Affected

To determine whether your Python environment is affected by GHSA-w476-p2h3-79g9, inspect your installed packages using pip:

pip show uv

Analyze the terminal output to locate any version of Uv in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.9.5), your application is affected.

Note: The pip show uv command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-843: Access of Resource Using Incompatible Type ('Type Confusion'), where the product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type. In Uv, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact In versions 0.9.4 and earlier of uv, tar archives containing PAX headers with file size overrides were not handled properly. As a result, an attacker could contrive a source distribution (as a tar archive) that would extract differently when installed via uv versus other Python package installers. The underlying parsing differential here originates with astral-tokio-tar, which disclosed this vulnerability as CVE-2025-62518. In practice, the impact of this vulnerability is **low**: only source distributions can be formatted as tar archives, and source distributions execute arbitrary code at build/installation time by definition. Consequently, a parser differential in tar extraction is strictly less powerful than the capabilities already exposed to an attacker who has the ability to control source distributions. However, this particular source of malleability in source distributions is unintentional and not operating by design, and therefore we consider it a vulnerability despite its overlap in capabilities with intended behavior. ### Patches Versions 0.9.5 and newer of uv address the vulnerability above. Users should upgrade to 0.9.5 or newer. ### Workarounds Users are advised to upgrade to version 0.9.5 or newer to address this advisory. Users should experience no breaking changes as a result of the patch above. ### References * See CVE-2025-62518 for the corresponding advisory against astral-tokio-tar

GHSA-w476-p2h3-79g9 Affected Uv Versions

1 component(s)
Fixed Versions:
0.9.5
Product / Package Ecosystem Affected Versions Fixed Version
uv
pypi/uv
PyPI
< 0.9.5
0.9.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/astral-sh/uv/security/advisories/GHSA-w476-p2h3-79g9
Uv Source Repository REPOSITORY
https://github.com/astral-sh/uv/pull/16387
Uv Source Repository REPOSITORY
https://github.com/astral-sh/uv
Security Fix Commit FIX COMMIT
https://github.com/astral-sh/uv/commit/ae450662d1546e9853f67a8c61a506d3a892d963
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-j5gw-2vrg-8fgx
Uv Release RELEASE
https://github.com/astral-sh/uv/releases/tag/0.9.5

Frequently Asked Questions

What is GHSA-w476-p2h3-79g9?
GHSA-w476-p2h3-79g9 is a security vulnerability in Uv involving uv has differential in tar extraction with PAX headers under CWE-843: Access of Resource Using Incompatible Type ('Type Confusion').
Which Uv versions are affected?
Affected versions include releases prior to 0.9.5 across affected packages: uv.
What version fixes GHSA-w476-p2h3-79g9?
Upgrading to 0.9.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is uv affected?
Yes, uv is affected in releases prior to 0.9.5. Upgrade your dependency to 0.9.5 or later.
What CWE is associated with GHSA-w476-p2h3-79g9?
GHSA-w476-p2h3-79g9 is classified under CWE-843: Access of Resource Using Incompatible Type ('Type Confusion') (The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.).
How can I check PyPI dependencies for GHSA-w476-p2h3-79g9?
Run the dependency tree command: 'pip show uv'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-w476-p2h3-79g9",
  "modified" : "2025-10-21T18:53:28Z",
  "published" : "2025-10-21T18:53:27Z",
  "aliases" : [ ],
  "summary" : "uv has differential in tar extraction with PAX headers",
  "details" : "### Impact\n\nIn versions 0.9.4 and earlier of uv, tar archives containing PAX headers with file size overrides were not handled properly. As a result, an attacker could contrive a source distribution (as a tar archive) that would extract differently when installed via uv versus other Python package installers.\n\nThe underlying parsing differential here originates with astral-tokio-tar, which disclosed this vulnerability as CVE-2025-62518.\n\nIn practice, the impact of this vulnerability is **low**: only source distributions can be formatted as tar archives, and source distributions execute arbitrary code at build/installation time by definition. Consequently, a parser differential in tar extraction is strictly less powerful than the capabilities already exposed to an attacker who has the ability to control source distributions. \n\nHowever, this particular source of malleability in source distributions is unintentional and not operating by design, and therefore we consider it a vulnerability despite its overlap in capabilities with intended behavior.\n\n### Patches\n\nVersions 0.9.5 and newer of uv address the vulnerability above. Users should upgrade to 0.9.5 or newer.\n\n### Workarounds\n\nUsers are advised to upgrade to version 0.9.5 or newer to address this advisory.\n\nUsers should experience no breaking changes as a result of the patch above.\n\n### References\n\n* See CVE-2025-62518 for the corresponding advisory against astral-tokio-tar",
  "severity" : [ ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "uv"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.9.5"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.9.4"
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  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/astral-sh/uv/security/advisories/GHSA-w476-p2h3-79g9"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/astral-sh/uv/pull/16387"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/astral-sh/uv/commit/ae450662d1546e9853f67a8c61a506d3a892d963"
  }, {
    "type" : "ADVISORY",
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  }, {
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    "url" : "https://github.com/astral-sh/uv"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/astral-sh/uv/releases/tag/0.9.5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-843" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-10-21T18:53:27Z",
    "nvd_published_at" : null
  }
}