CVE-2025-12978 CVE-2025-12978
Remote attackers can manipulate log tags in Fluent Bit input plugins to redirect records and inject forged data due to flawed key validation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-12978?
CVE-2025-12978 is a medium-severity vulnerability in FluentBit Fluent Bit, published on 24 Nov 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins contain a flaw in the tag_key validation logic that fails to enforce exact key-length matching. This allows crafted inputs where a tag prefix is incorrectly treated as a full match. A remote attacker with authenticated or exposed access to these input endpoints can exploit this behavior to manipulate tags and redirect records to unintended destinations. This compromises the authenticity of ingested logs and can allow injection of forged data, alert flooding and routing manipulation.
Which versions are affected by CVE-2025-12978?
1 open source package ship an affected version, including fluent-bit. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
fluent-bit Bitnami | From 4.1.0 | 4.1.1 |
Products include Treasuredata Fluent Bit.
How do I fix CVE-2025-12978?
Upgrade fluent-bit to 4.1.1 or later.
Is CVE-2025-12978 being exploited?
There is no known exploitation of CVE-2025-12978 in the wild and no public exploit code.
Other vulnerabilities in FluentBit Fluent Bit
Sources
Also known as BIT-fluent-bit-2025-12978, GHSA-7qw4-6c7x-f3pj.