CVE-2025-35434: CISA Thorium does not validate TLS connections to Elasticsearch

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% 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-295

Description

CISA Thorium does not validate TLS certificates when connecting to Elasticsearch. An unauthenticated attacker with access to a Thorium cluster could impersonate the Elasticsearch service. Fixed in 1.1.2.

Affected products

CISA Thorium: 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/models/backends/setup/elastic_setup.rs#L36-L43
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-2025-35434

Get alerted when CVE-2025-35434 or the next vulnerability affects your stack