Thorium: Improper Certificate Validation
CVE-2025-35434 is a critical-severity improper certificate validation vulnerability in Thorium from CISA, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 1.1.2 as the first without the flaw, so updating Thorium to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.2% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Thorium to 1.1.2 or a later version.
- Read the advisory on raw.githubusercontent.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 2.3 | Low | CNA |
| CVSS 3.1 | 4.2 | Medium | CNA |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Certificate Validation
The product does not validate, or incorrectly validates, a certificate.
How developers prevent this class of flaw
- Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
- If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
More Improper Certificate Validation vulnerabilities (CWE-295)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/cisagov/thorium/releases/tag/1.1.2Release Notes
Third-party and government advisories
- cve.org/CVERecord?id=CVE-2025-35434Third Party Advisory
Other references
Other vulnerabilities in Thorium
- 7.5 High severity
- 8.8 High severity
- 7.5 High severity
Recent Improper Certificate Validation vulnerabilities
- 7.5 High severity
- 9.0 Critical severity
- 8.8 High severity
- 7.7 High severity
- 8.8 High severity
- 8.8 High severity
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