CVE-2026-23956
Published: 22 January 2026
Summary
CVE-2026-23956 is a high-severity Inefficient Regular Expression Complexity (CWE-1333) vulnerability in Lxsmnsyc Seroval. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 8.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct remote exploitation of library deserialization flaw (oversized/backtracking RegExp) to trigger memory/CPU exhaustion and application DoS.
NVD Description
seroval facilitates JS value stringification, including complex structures beyond JSON.stringify capabilities. In versions 1.4.0 and below, overriding RegExp serialization with extremely large patterns can exhaust JavaScript runtime memory during deserialization. Additionally, overriding RegExp serialization with patterns that trigger catastrophic backtracking…
more
can lead to ReDoS (Regular Expression Denial of Service). This issue has been fixed in version 1.4.1.
Deeper analysisAI
CVE-2026-23956 affects the seroval JavaScript library, which enables stringification of JavaScript values including complex structures beyond the capabilities of JSON.stringify. In versions 1.4.0 and earlier, the vulnerability arises from overriding RegExp serialization with extremely large patterns, which can exhaust JavaScript runtime memory during deserialization. Additionally, patterns that trigger catastrophic backtracking can cause ReDoS (Regular Expression Denial of Service). The issue is classified under CWE-1333 with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Attackers can exploit this vulnerability remotely over the network with low complexity, requiring no privileges, authentication, or user interaction. By crafting malicious serialized payloads with oversized or backtracking-prone RegExp patterns, unauthenticated attackers can trigger memory exhaustion or prolonged CPU usage during deserialization, resulting in denial of service that disrupts application availability.
The seroval security advisory and associated commit confirm the issue has been addressed in version 1.4.1. Security practitioners should upgrade to this patched version to mitigate the vulnerability, as detailed in the GitHub security advisory (GHSA-hx9m-jf43-8ffr) and the fixing commit (ce9408ebc87312fcad345a73c172212f2a798060).
Details
- CWE(s)