CVE-2026-2869 in janet
Summary
by MITRE • 02/21/2026
A vulnerability was identified in janet-lang janet up to 1.40.1. Affected by this vulnerability is the function janetc_varset of the file src/core/specials.c of the component handleattr Handler. The manipulation leads to out-of-bounds read. The attack can only be performed from a local environment. The exploit is publicly available and might be used. Upgrading to version 1.41.0 addresses this issue. The identifier of the patch is 2fabc80151a2b8834ee59cda8a70453f848b40e5. The affected component should be upgraded.
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Analysis
by VulDB Data Team • 02/27/2026
The vulnerability CVE-2026-2869 represents a critical out-of-bounds read flaw within the janet-lang janet programming language implementation, specifically affecting versions prior to 1.41.0. This vulnerability resides in the janetc_varset function located within the src/core/specials.c file of the handleattr Handler component, making it a significant concern for systems that rely on this scripting language for various operations. The flaw manifests when the function processes variable assignments and attribute handling, creating an opportunity for memory access violations that could potentially lead to system instability or information disclosure.
The technical nature of this vulnerability stems from improper bounds checking within the janetc_varset function, which fails to validate array indices or memory access limits when processing certain attribute assignments. This particular implementation flaw allows attackers with local system access to manipulate memory locations beyond the intended boundaries, potentially reading sensitive data from adjacent memory regions. The vulnerability is classified as a local privilege escalation vector since exploitation requires physical or local system access, though the availability of public exploits increases the potential threat surface. The out-of-bounds read condition creates an opportunity for attackers to extract memory contents, potentially including stack variables, heap data, or other sensitive information that might be stored in adjacent memory locations.
The operational impact of this vulnerability extends beyond simple memory corruption, as it could enable attackers to gather sensitive information from the application's memory space, potentially exposing credentials, cryptographic keys, or other confidential data. The local execution requirement means that attackers must already have access to the system to exploit this vulnerability, but this limitation does not diminish its severity since local access often represents a significant compromise of system security. The vulnerability's presence in a core language component like janetc_varset suggests that it could affect numerous applications and scripts that depend on the janet runtime for execution, particularly those handling user input or configuration data through attribute assignment mechanisms.
Mitigation strategies for CVE-2026-2869 center on the immediate upgrade to janet version 1.41.0, which incorporates the patch identified by commit hash 2fabc80151a2b8834ee59cda8a70453f848b40e5. This upgrade process should be prioritized across all systems running affected versions of the janet language implementation. Organizations should also conduct thorough vulnerability assessments to identify any applications or services that might be leveraging the vulnerable janet components, particularly those handling sensitive data or user inputs through attribute assignment operations. Additionally, implementing runtime monitoring and memory protection mechanisms such as address space layout randomization and stack canaries can provide additional defense-in-depth measures against potential exploitation attempts.
This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in software implementations, and represents a clear example of how seemingly minor memory management flaws can create significant security risks. The ATT&CK framework categorizes this vulnerability under privilege escalation and defense evasion techniques, as local exploitation can lead to broader system compromise. The availability of public exploits for this vulnerability increases its risk profile significantly, as it reduces the barrier to exploitation and potentially enables automated attack tools to target vulnerable systems. Security teams should consider this vulnerability as part of their comprehensive vulnerability management program and ensure that all janet-based applications are updated to prevent potential exploitation attempts.