# CVE-2025-12977: CVE-2025-12977

> Attackers can inject special characters into tag keys to cause path traversal, log misrouting, or record forgery in Fluent Bit input plugins.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Nov 2025
- **Updated:** 7 Jan 2026
- **Also known as:** AZL-71080, AZL-71102, BIT-fluent-bit-2025-12977, GHSA-v498-rhc6-28g9

## What is CVE-2025-12977?

CVE-2025-12977 is a critical path traversal vulnerability in FluentBit Fluent Bit, published on 24 Nov 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize tag_key inputs. An attacker with network access or the ability to write records into Splunk or Elasticsearch can supply tag_key values containing special characters such as newlines or ../ that are treated as valid tags. Because tags influence routing and some outputs derive filenames or contents from tags, this can allow newline injection, path traversal, forged record injection, or log misrouting, impacting data integrity and log routing.

Weakness: CWE-1287 (Improper Validation of Specified Type of Input)

## Which versions are affected by CVE-2025-12977?

1 open source package ship an affected version, including fluent-bit. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `fluent-bit` | Bitnami | From 4.1.0 | 4.1.1 |

Products: Treasuredata Fluent Bit.

## How do I fix CVE-2025-12977?

Upgrade fluent-bit to 4.1.1 or later.

## Is CVE-2025-12977 being exploited?

There is no known exploitation of CVE-2025-12977 in the wild and no public exploit code.

## Other vulnerabilities in FluentBit Fluent Bit

- [CVE-2024-4323](https://insights.sbomify.com/CVE-2024-4323/): Fluent Bit Memory Corruption Vulnerability (critical 9.8)
- [CVE-2021-36088](https://insights.sbomify.com/CVE-2021-36088/): Use after free in n/a (critical 9.8)
- [CVE-2025-12970](https://insights.sbomify.com/CVE-2025-12970/): CVE-2025-12970 (high 8.8)
- [CVE-2021-46878](https://insights.sbomify.com/CVE-2021-46878/): Use after free in n/a (high 7.8)
- [CVE-2021-46879](https://insights.sbomify.com/CVE-2021-46879/): Memory corruption in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-12977 and fix it if it is affected.

What it is: CVE-2025-12977 is a critical path traversal vulnerability in FluentBit Fluent Bit, published on 24 Nov 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-12977 in the wild and no public exploit code.

Affected packages and fixed versions:
- fluent-bit (Bitnami): affected from 4.1.0; fixed in 4.1.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-12977/ (Markdown: https://insights.sbomify.com/CVE-2025-12977/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-12977
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-12977
- OSV: https://osv.dev/vulnerability/CVE-2025-12977

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-12977/
Summaries are generated and may contain mistakes; the official description above is the record.