VulnerabilityPublished 17 Sep 2025Updated 30 Sep 2025

CVE-2025-35434: CISA Thorium · Improper Certificate Validation

Affects CISA ThoriumSource CVE Database V5

Not known to be exploited · CVSS 4.2 Medium · fixed in 1.1.2 : update CISA Thorium when convenient.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score

4.2Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.1.2

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector: Adjacent
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
CISA Thorium	Affected =1.0.0	Fixed in–

AI-suggested

Upgrade CISA Thorium to version 1.1.2 or later, where the certificate validation issue is fixed.
Implement strict network segmentation to restrict access to Thorium clusters, limiting exposure to only trusted hosts and networks.
Use network-level encryption and monitoring tools to detect anomalous traffic patterns indicative of MITM attacks.
Employ mutual TLS authentication between Thorium and Elasticsearch to ensure both endpoints validate each other’s certificates.
Regularly audit and verify TLS configurations and certificates used by Thorium and Elasticsearch services to ensure compliance with security best practices.
Monitor logs for unusual connection attempts or certificate anomalies.
If upgrading immediately is not feasible, consider deploying network-level protections such as VPNs or IPsec tunnels to secure communications between Thorium and Elasticsearch.

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.

Impact

For European organizations using CISA Thorium 1.0.0 integrated with Elasticsearch, this vulnerability poses a risk of man-in-the-middle attacks on the communication channel between Thorium and Elasticsearch. This could lead to unauthorized data exposure or manipulation, undermining trust in security monitoring and analytics data. Confidentiality impact is limited but non-negligible, especially if sensitive logs or security event data are transmitted. Integrity impact could affect decision-making based on corrupted or falsified data. Availability is not impacted. Given the medium CVSS score and the requirement for network access to the Thorium cluster, the threat is moderate but should not be ignored. Organizations in regulated sectors such as finance, healthcare, and critical infrastructure in Europe could face compliance risks if security monitoring data is compromised. Additionally, the lack of authentication requirement lowers the barrier for exploitation if network access is gained, increasing risk in environments with insufficient network segmentation or monitoring.

CWE-295Improper Certificate Validation (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not validate, or incorrectly validates, a certificate.
Architecture and Design · Implementation
Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
Implementation
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.
OWASP Cheat Sheets
Transport Layer Protection (opens in a new tab)
TLS Cipher String (opens in a new tab)
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V9.2.1 (opens in a new tab)
V1.9.2 (opens in a new tab)
V2.8.5 (opens in a new tab)
Attack patterns
Creating a Rogue Certification Authority Certificate (opens in a new tab)
Signature Spoofing by Improper Validation (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 1 Oct 2025, 00:16 UTC

WeaknessesCWE-295

Technical details

References

Community reviews

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