VulnerabilityPublished 27 Oct 2025Updated 24 Feb 2026

CVE-2025-12205: Kamailio · Use After Free

Affects KamailioSource CVE Database V5

Public exploit available · CVSS 4.8 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 4.0 base score

4.8Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Base metrics

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

Threat metrics

Exploit Maturity: POC

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

Attack Vector: Local: The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
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: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system 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 to the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to 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.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

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 or the CVSS exploit maturity 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
Kamailio	Affected =5.5	Fixed in–

AI-suggested

To mitigate CVE-2025-12205, organizations should implement strict local access controls to prevent unauthorized users from accessing the Kamailio server or its configuration files. Employ file system permissions to restrict write access to configuration files only to trusted administrators. Regularly monitor and audit configuration files for unauthorized changes using file integrity monitoring tools. Consider isolating Kamailio instances in hardened environments or containers to limit local attack surfaces. Until an official patch is released, applying runtime protections such as AddressSanitizer or other memory safety tools during testing may help detect exploitation attempts. Additionally, maintain up-to-date backups of configuration files to enable quick recovery in case of tampering. Engage with the Kamailio community or vendors for updates and patches, and plan for timely patch application once available.

Description

A vulnerability was detected in Kamailio 5.5. The affected element is the function sr_push_yy_state of the file src/core/cfg.lex of the component Configuration File Handler. The manipulation results in use after free. The attack must be initiated from a local position. The exploit is now public and may be used. The real existence of this vulnerability is still doubted at the moment. This attack requires manipulating config files which might not be a realistic scenario in many cases. The vendor was contacted early about this disclosure but did not respond in any way.

Impact

The potential impact of CVE-2025-12205 includes partial compromise of the Kamailio SIP server's confidentiality, integrity, and availability. Exploiting the use-after-free could cause service crashes or enable an attacker to execute arbitrary code with local privileges, potentially disrupting VoIP services. Given Kamailio's role in handling SIP signaling for voice communications, such disruptions could affect telephony availability and reliability. However, the requirement for local access and configuration file manipulation reduces the likelihood of widespread exploitation. Organizations with lax local access controls or shared environments are at higher risk. The absence of vendor patches prolongs exposure, increasing the window for potential exploitation. Overall, the impact is moderate but could be significant in sensitive telephony infrastructures or multi-tenant environments where local access is less restricted.

Summary

CVE-2025-12205 is a use-after-free vulnerability identified in Kamailio version 5.5, an open-source SIP server widely used for VoIP communications. The flaw resides in the sr_push_yy_state function of the src/core/cfg.lex file, which is part of the configuration file handler component. A use-after-free occurs when the program continues to use memory after it has been freed, potentially leading to memory corruption, crashes, or arbitrary code execution. However, exploitation of this vulnerability requires an attacker to have local access to the system and the ability to manipulate Kamailio configuration files. This significantly limits the attack vector, as remote exploitation is not feasible without prior compromise. The vulnerability was publicly disclosed with a CVSS v4.0 score of 4.8, indicating medium severity, with attack vector local (AV:L), low attack complexity (AC:L), no privileges required beyond local access (PR:L), and no user interaction needed (UI:N). The vendor has not issued any response or patch, and the exploit code is publicly available, although the real-world impact remains uncertain due to the constrained exploitation scenario. The vulnerability could lead to partial confidentiality, integrity, and availability impacts if exploited, such as service disruption or unauthorized configuration changes. Organizations running Kamailio 5.5 should consider this vulnerability seriously, especially in environments where local access controls are weak or where configuration files might be exposed to unauthorized modification.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Feb 2026, 21:35 UTC

Technical details

References

Community reviews

Related threats