CVE-2025-34271VulnerabilityPublished 30 Oct 2025Updated 17 Nov 2025

CVE-2025-34271: Nagios Log Server · Cleartext Transmission

Affects Nagios Log ServerSource CVE Database V5

Not known to be exploited · CVSS 8.7 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

8.7High

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 30 Oct 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 2026-10-25.

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
Nagios Log Server	Affected =0	Fixed in–

AI-suggested

1. Upgrade Nagios Log Server to version 2024R2.0.2 or later, where the vulnerability is patched and all cluster communications are encrypted. 2. Verify and enforce encryption settings for all inter-node communications within the cluster, ensuring no fallback to unencrypted channels. 3. Implement network segmentation to isolate cluster communication traffic from general network traffic, reducing the risk of interception. 4. Deploy network monitoring and intrusion detection systems to detect unusual authentication attempts or anomalous cluster node behavior. 5. Conduct regular audits of cluster configurations and credentials to identify and remediate any unauthorized access. 6. Use strong, unique credentials for cluster nodes and service accounts, and rotate them periodically. 7. Educate network and security teams about the vulnerability and signs of exploitation to improve incident response readiness. 8. Consider deploying additional encryption layers such as VPNs or IPsec tunnels for cluster communication if feasible. 9. Maintain up-to-date asset inventories to quickly identify affected Nagios Log Server deployments. 10. Engage with Nagios support or security advisories to stay informed about any emerging threats or patches related to this vulnerability.

Description

CVE-2025-34271 is a high-severity vulnerability in Nagios Log Server versions prior to 2024R2.0.2 affecting the cluster manager component. The flaw involves cleartext transmission of sensitive credentials between cluster nodes over unencrypted channels, even when SSL/TLS is enabled. An attacker with network access can intercept these credentials, potentially allowing unauthorized authentication as a cluster node or service account. This can lead to lateral movement, unauthorized access, and system compromise within affected environments. No known exploits are currently reported in the wild. The vulnerability has a CVSS 4.0 base score of 8.7, reflecting its high impact and ease of exploitation without authentication or user interaction.

Impact

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of monitoring infrastructure. Nagios Log Server is widely used for centralized log management and monitoring, often deployed in critical sectors such as finance, telecommunications, energy, and government. Exposure of cluster credentials could allow attackers to gain persistent access to monitoring systems, manipulate logs, or disrupt monitoring capabilities, potentially masking other malicious activities. This could lead to delayed detection of intrusions, data breaches, or operational outages. The ability to move laterally within networks using compromised cluster credentials increases the attack surface and risk of broader compromise. Organizations relying on Nagios Log Server clusters for compliance reporting or security monitoring may face regulatory and reputational consequences if this vulnerability is exploited. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially given the ease of exploitation and high impact. European entities with stringent data protection laws (e.g., GDPR) must prioritize remediation to avoid legal and financial penalties.

CWE-319Cleartext Transmission of Sensitive Information (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product transmits sensitive or security-critical data in cleartext in a communication channel that can be sniffed by unauthorized actors.
Architecture and Design
Before transmitting, encrypt the data using reliable, confidentiality-protecting cryptographic protocols.
Implementation
When using web applications with SSL, use SSL for the entire session from login to logout, not just for the initial login page.
Implementation
When designing hardware platforms, ensure that approved encryption algorithms (such as those recommended by NIST) protect paths from security critical data to trusted user applications.
OWASP Cheat Sheets
Transport Layer Protection (opens in a new tab)
TLS Cipher String (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
Cryptographic Storage (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.1 (opens in a new tab)
V9.2.2 (opens in a new tab)
V1.9.1 (opens in a new tab)
Attack patterns
Session Sidejacking (opens in a new tab)
Harvesting Information via API Event Monitoring (opens in a new tab)
Signature Spoofing by Mixing Signed and Unsigned Content (opens in a new tab)
Sniff Application Code (opens in a new tab)
Interception (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 24 Nov 2025, 22:19 UTC

WeaknessesCWE-319

Technical details

References

Community reviews

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