CVE-2021-3422 Indexer denial-of-service via malformed S2S request
Attackers can cause denial of service in Splunk Enterprise by sending malformed S2S requests to instances configured to index Universal Forwarder traffic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-3422?
CVE-2021-3422 is a high-severity denial of service vulnerability in Splunk Splunk, published on 25 Mar 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The lack of validation of a key-value field in the Splunk-to-Splunk protocol results in a denial-of-service in Splunk Enterprise instances configured to index Universal Forwarder traffic. The vulnerability impacts Splunk Enterprise versions before 7.3.9, 8.0 versions before 8.0.9, and 8.1 versions before 8.1.3. It does not impact Universal Forwarders. When Splunk forwarding is secured using TLS or a Token, the attack requires compromising the certificate or token, or both. Implementation of either or both reduces the severity to Medium.
Which versions are affected by CVE-2021-3422?
It affects 1 product.
Products include Splunk Splunk.
How do I fix CVE-2021-3422?
No fix has been published for CVE-2021-3422 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-3422 being exploited?
There is no known exploitation of CVE-2021-3422 in the wild and no public exploit code.
Other vulnerabilities in Splunk Splunk
- CVE-2026-20253 Splunk Enterprise Missing Authentication for Critical Function
- CVE-2026-76268 Missing Authentication for Critical Function in the Patroni REST API in Splunk Enterprise
- CVE-2026-76284 Improper Neutralization in Splunk Enterprise
- CVE-2026-76285 Improper Adherence to Coding Standards in Splunk Enterprise
- CVE-2017-17067 Auth bypass in n/a
Sources
Also known as GHSA-4c93-wvp2-c39r.