VulnerabilityPublished 12 Nov 2025

CVE-2025-20378: Splunk Enterprise · A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks.

Affects Splunk EnterpriseSource CVE Database V5

Not known to be exploited · CVSS 3.1 Low.

Data as of 26 Oct 2026, 09:15 UTC

CVSS 3.1 base score

3.1Low

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: None: There is no loss of integrity within 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 12 Nov 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 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
Splunk Splunk Enterprise	Affected =10.0 =9.4 =9.3 =9.2	Fixed in–

AI-suggested

1. Upgrade Splunk Enterprise and Splunk Cloud Platform to versions 10.0.1, 9.4.5, 9.3.7, 9.2.9 or later where the vulnerability is fixed. 2. Implement strict validation and whitelisting of URLs accepted in the 'return_to' parameter to prevent redirection to untrusted external sites. 3. Configure web application firewalls (WAFs) to detect and block suspicious redirect URLs targeting Splunk login endpoints. 4. Conduct targeted user awareness training emphasizing the risks of clicking unexpected or suspicious links, especially those purporting to be from internal tools like Splunk. 5. Monitor Splunk web access logs for unusual redirect parameter usage or spikes in login endpoint requests with external URLs. 6. Consider implementing multi-factor authentication (MFA) to reduce the risk of credential compromise if phishing occurs. 7. Use URL rewriting or proxying to restrict redirects to internal domains only. 8. Coordinate with security teams to integrate phishing detection and response workflows that consider this vulnerability’s exploitation vector.

Description

In Splunk Enterprise versions below 10.0.1, 9.4.5, 9.3.7, 9.2.9, and Splunk Cloud Platform versions below 10.0.2503.5, 9.3.2411.111, and 9.3.2408.121, an unauthenticated attacker could craft a malicious URL using the `return_to` parameter of the Splunk Web login endpoint. When an authenticated user visits the malicious URL, it could cause an unvalidated redirect to an external malicious site. To be successful, the attacker has to trick the victim into initiating a request from their browser. The unauthenticated attacker should not be able to exploit the vulnerability at will.

Impact

For European organizations, the primary impact of CVE-2025-20378 is an increased risk of successful phishing attacks leveraging trusted Splunk URLs. Since Splunk is widely used for security information and event management (SIEM), a phishing attack exploiting this vulnerability could lead to credential theft or malware infection, potentially compromising sensitive security monitoring environments. Although the vulnerability itself does not allow direct unauthorized access or data manipulation, successful phishing could lead to broader security incidents. Organizations in sectors such as finance, energy, government, and critical infrastructure that rely heavily on Splunk for security monitoring are particularly at risk. The need for user interaction limits the scope, but targeted spear-phishing campaigns could exploit this vector effectively. The vulnerability could also erode user trust in internal security tools if exploited.

Summary

CVE-2025-20378 is a web application vulnerability affecting Splunk Enterprise versions below 10.0.1, 9.4.5, 9.3.7, 9.2.9, and corresponding Splunk Cloud Platform versions. The vulnerability arises because the 'return_to' parameter in the Splunk Web login endpoint accepts user-controlled input that specifies a URL to which the user is redirected after login. This parameter is not properly validated, allowing an attacker to craft a URL that redirects authenticated users to arbitrary external sites. The attacker does not need authentication but must trick a user into clicking the malicious URL. The vulnerability facilitates phishing attacks by redirecting users to malicious sites that may attempt credential theft or malware delivery. The CVSS score is 3.1 (low severity), reflecting that exploitation requires user interaction and has limited impact on confidentiality, integrity, and availability. There are no known exploits in the wild, and the vulnerability does not allow direct system compromise. However, it increases the risk of social engineering attacks leveraging Splunk’s trusted domain. The vulnerability was reserved in October 2024 and published in November 2025. No patches or workarounds are explicitly listed in the provided data, but upgrading to fixed versions is implied.

References

advisory.splunk.com/advisories/SVD-2025-1101 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 19 Nov 2025, 19:04 UTC

Technical details

References

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