CVE-2025-35430: CISA Thorium insecure downloaded file path validation

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-17 · updated 2026-06-17
Weakness: CWE-22

Description

CISA Thorium does not adequately validate the paths of downloaded files via 'download_ephemeral' and 'download_children'. A remote, authenticated attacker could access arbitrary files subject to file system permissions. Fixed in 1.1.2.

Affected products

CISA Thorium: from 1.0.0 before 1.1.2 — fixed in 1.1.2

How to fix

Upgrade to a fixed version: CISA Thorium 1.1.2. Check the vendor advisory for mitigations.

References

https://github.com/cisagov/thorium/blob/main/api/src/utils/bounder.rs#L120-L158
https://github.com/cisagov/thorium/releases/tag/1.1.2
https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2025/va-25-259-01.json
https://www.cve.org/CVERecord?id=CVE-2025-35430

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