CVE-2026-23956
Lxsmnsyc Seroval ≤ 1.4.1
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
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 Endpoint Denial of Service (T1499); ranked at the 44th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
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).
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3669
Vulnerability Data
seroval facilitates JS value stringification, including complex structures beyond JSON.stringify capabilities. In versions 0.2.0 through 1.4.0, 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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover inefficient regex patterns via performance or static analysis.
Development standards and tools can require safe regex construction and forbid known exponential patterns.
Denial-of-service protections limit resource exhaustion caused by expensive regex evaluation.
Input validation can constrain data that would otherwise trigger worst-case regex complexity.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect and reject regex patterns with exponential worst-case complexity.
Secure coding standards explicitly prohibit or limit the use of inefficient regular expressions.