CVE-2026-23956 seroval affected by Denial of Service via RegExp serialization

High 7.5 Published 22 Jan 2026 Updated 20 May 2026

Attackers can cause denial of service in applications using seroval by providing malicious RegExp patterns that exhaust memory or trigger catastrophic backtracking.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-23956?

CVE-2026-23956 is a high-severity denial of service vulnerability in lxsmnsyc seroval, published on 22 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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 can lead to ReDoS (Regular Expression Denial of Service). This issue has been fixed in version 1.4.1.

Weakness: CWE-1333

Which versions are affected by CVE-2026-23956?

2 open source packages ship an affected version, including seroval. It affects 1 product.

Package	Affected	Fixed in
`seroval` npm	From `0.2.0`	`1.4.1`
`seroval` npm	From `0.2.0`	`1.4.1`

Products include Lxsmnsyc Seroval.

How do I fix CVE-2026-23956?

Upgrade seroval to 1.4.1 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-23956 being exploited?

There is no known exploitation of CVE-2026-23956 in the wild and no public exploit code.

Sources

Also known as GHSA-hx9m-jf43-8ffr.