CVE-2026-2655VulnerabilityPublished 18 Feb 2026Updated 23 Feb 2026

CVE-2026-2655: ChaiScript · Use After Free

Affects ChaiScriptSource CVE Database V5

Not known to be exploited · CVSS 2.0 Low.

Data as of 26 Oct 2026, 07:57 UTC

CVSS 4.0 base score

2.0Low

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Base metrics

Attack Vector: Local
Attack Complexity: High
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
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: High: The successful attack depends on the evasion or circumvention of security-enhancing techniques in place that would otherwise hinder the attack. These include: Evasion of exploit mitigation techniques, for example, circumvention of address space randomization (ASLR) or data execution prevention (DEP) must be performed for the attack to be successful; Obtaining target-specific secrets. The attacker must gather some target-specific secret before the attack can be successful. A secret is any piece of information that cannot be obtained through any amount of reconnaissance. To obtain the secret the attacker must perform additional attacks or break otherwise secure measures (e.g. knowledge of a secret key may be needed to break a crypto channel). This operation must be performed for each attacked target.
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: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within 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 18 Feb 2026
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
ChaiScript	Affected =6.0 =6.1.0	Fixed in–

AI-suggested

To mitigate CVE-2026-2655, organizations should: 1) Restrict local access to systems running applications embedding ChaiScript to trusted users only. 2) Monitor for updates from the ChaiScript project and apply patches promptly once available. 3) Conduct code reviews and audits of scripts and integrations using ChaiScript to identify and limit use of the vulnerable function or unsafe memory handling patterns. 4) Employ sandboxing or containerization to isolate applications using ChaiScript, reducing the impact of potential exploitation. 5) Consider upgrading to newer versions of ChaiScript if and when they address this vulnerability. 6) Implement strict privilege separation to minimize the ability of local users to exploit the vulnerability. 7) Use memory safety tools or runtime protections (e.g., ASLR, DEP) to reduce exploitation success likelihood.

Description

A vulnerability was detected in ChaiScript up to 6.1.0. The impacted element is the function chaiscript::str_less::operator of the file include/chaiscript/chaiscript_defines.hpp. The manipulation results in use after free. The attack requires a local approach. The attack requires a high level of complexity. The exploitability is regarded as difficult. The exploit is now public and may be used. The project was informed of the problem early through an issue report but has not responded yet.

Impact

The primary impact of CVE-2026-2655 is potential memory corruption leading to application instability or crashes in software embedding vulnerable versions of ChaiScript. While the vulnerability theoretically could be leveraged for arbitrary code execution, the high complexity and local access requirements significantly limit its practical exploitability. Organizations using ChaiScript in environments where local users have script execution capabilities may face risks of denial-of-service or unexpected behavior. However, remote exploitation or widespread compromise is unlikely. The absence of a patch means affected systems remain vulnerable until mitigations or updates are applied. The impact is thus mostly confined to stability and reliability concerns rather than large-scale data breaches or system takeovers.

Summary

CVE-2026-2655 identifies a use-after-free vulnerability in the ChaiScript scripting engine, specifically within the chaiscript::str_less::operator function defined in include/chaiscript/chaiscript_defines.hpp. This vulnerability arises when the function improperly manages memory, leading to a scenario where a pointer is used after the referenced memory has been freed. Such use-after-free conditions can cause undefined behavior, including application crashes, memory corruption, or potentially arbitrary code execution under certain conditions. However, exploitation requires local access to the system, a high degree of technical skill, and the ability to trigger the vulnerable code path. The vulnerability affects ChaiScript versions 6.0 and 6.1.0, with no patches currently available and no public exploits observed in the wild. The CVSS 4.0 vector indicates low severity (score 2), reflecting the difficulty of exploitation and limited impact scope. The ChaiScript project has been notified but has not yet responded or released a fix. Given ChaiScript's role as an embedded scripting language in applications, the vulnerability could impact software that integrates these versions, especially if local users can execute or influence script operations.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 28 Feb 2026, 13:35 UTC

Technical details

References

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