CVE-2025-12972VulnerabilityPublished 24 Nov 2025Updated 7 Jan 2026

CVE-2025-12972: FluentBit Fluent Bit · Path Traversal

Affects FluentBit Fluent BitSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 07:57 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.9% chance of exploitation in 30 days – higher than 60% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: None: The vulnerable system can be exploited without any interaction from any user.
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: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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 24 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 2026-10-26.

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
FluentBit Fluent Bit	Affected =0	Fixed in–

AI-suggested

1. Immediately review Fluent Bit configurations to ensure the File option is explicitly set in the out_file plugin to prevent reliance on tag-derived file names. 2. Implement strict input validation and sanitization for all tag values before they reach Fluent Bit, filtering out path traversal sequences and other malicious characters. 3. Restrict network access to Fluent Bit instances, limiting log input sources to trusted and authenticated systems only. 4. Monitor file system changes in directories used by Fluent Bit for unexpected file creations or modifications. 5. Employ application-level sandboxing or containerization to limit the impact of unauthorized file writes. 6. Stay updated with Fluent Bit vendor advisories for patches or official fixes and apply them promptly once available. 7. Consider deploying Web Application Firewalls (WAFs) or Intrusion Detection Systems (IDS) with rules targeting path traversal attempts in log tags. 8. Conduct regular security audits and penetration tests focusing on log ingestion pipelines to detect similar vulnerabilities.

Description

Fluent Bit out_file plugin does not properly sanitize tag values when deriving output file names. When the File option is omitted, the plugin uses untrusted tag input to construct file paths. This allows attackers with network access to craft tags containing path traversal sequences that cause Fluent Bit to write files outside the intended output directory.

Impact

For European organizations, this vulnerability could lead to unauthorized file writes on systems running Fluent Bit, potentially allowing attackers to alter log files, inject malicious content, or disrupt log integrity. This undermines trust in logging data, which is critical for incident response and compliance with regulations such as GDPR. While it does not directly compromise confidentiality or availability, the integrity impact can facilitate further attacks or cover tracks of malicious activity. Organizations relying heavily on Fluent Bit for centralized logging, especially in cloud, container, or microservices environments, are at higher risk. The vulnerability could also affect managed service providers and cloud platforms operating in Europe that use Fluent Bit internally or offer it as part of their logging solutions. The risk is heightened in environments where Fluent Bit instances are exposed to untrusted networks or receive logs from external sources without strict validation.

CWE-35Path Traversal: '.../...//' (opens in a new tab)
Variant weaknessOWASP Top 10 A01:2021: Broken Access Control (opens in a new tab)
The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize '.../...//' (doubled triple dot slash) sequences that can resolve to a location that is outside of that directory.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP ASVS 4.0.3
V12.3.1 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Jan 2026, 19:44 UTC

WeaknessesCWE-35

Technical details

References

Community reviews

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