CVE-2021-31559 S2S TcpToken authentication bypass
Attackers can bypass TCP Token authentication to write arbitrary events to indexes in Splunk Enterprise Indexers configured with this feature.
- 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-2021-31559?
CVE-2021-31559 is a high-severity authentication bypass vulnerability in Splunk Splunk, published on 6 May 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A crafted request bypasses S2S TCP Token authentication writing arbitrary events to an index in Splunk Enterprise Indexer 8.1 versions before 8.1.5 and 8.2 versions before 8.2.1. The vulnerability impacts Indexers configured to use TCPTokens. It does not impact Universal Forwarders.
Weakness: CWE-288
Which versions are affected by CVE-2021-31559?
It affects 1 product.
Products include Splunk Splunk.
How do I fix CVE-2021-31559?
No fix has been published for CVE-2021-31559 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2021-31559 being exploited?
There is no known exploitation of CVE-2021-31559 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-g37x-8fq5-rmrc.