VulnerabilityPublished 22 Jan 2026

CVE-2026-23957: lxsmnsyc seroval · Unthrottled Resource Allocation

Affects lxsmnsyc serovalSource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 1.4.1 soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.4.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Jan 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 26 Oct 2026.

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 or the CVSS exploit maturity 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

Upgrade seroval and lxsmnsyc/seroval to 1.4.1.

Affected software

Product	Affected	Fixed in
lxsmnsycseroval	Affected <1.4.1	Fixed in 1.4.1
GitHublxsmnsyc/seroval`pkg:github/lxsmnsyc/seroval`Other threats	Affected <1.4.1	Fixed in 1.4.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade all instances of the lxsmnsyc seroval library to version 1.4.1 or later immediately to apply the fix that enforces resource allocation limits during deserialization.
Implement strict input validation and sanitization on all data received from untrusted sources before deserialization to prevent manipulation of array lengths or other serialized data fields.
Employ runtime monitoring and anomaly detection to identify unusual CPU or memory usage patterns indicative of resource exhaustion attacks during deserialization.
Use application-layer rate limiting and network-level protections such as Web Application Firewalls (WAFs) to limit the frequency and volume of requests that could trigger the vulnerability.
Conduct regular security audits and code reviews focusing on serialization/deserialization logic to identify and remediate similar resource allocation issues.
Develop incident response plans that include detection and mitigation strategies for denial-of-service attacks targeting serialization components.
Where feasible, isolate services using seroval in separate containers or virtual machines to limit the blast radius of potential DoS attacks.

Description

CVE-2026-23957 is a high-severity vulnerability in the lxsmnsyc seroval library versions prior to 1.4.1. The flaw arises from the allocation of resources without limits or throttling during the deserialization process when an attacker manipulates encoded array lengths to excessively large values. This causes a significant increase in processing time, leading to a denial-of-service (DoS) condition. The vulnerability does not impact confidentiality or integrity but severely affects availability. Exploitation requires no authentication or user interaction and can be triggered remotely over the network. The issue has been resolved in version 1.4.1.

Impact

For European organizations, this vulnerability poses a significant risk to service availability. Organizations using seroval in web applications, APIs, or backend services that handle external input could face denial-of-service attacks that disrupt business operations, degrade user experience, or cause downtime. Critical sectors such as finance, healthcare, telecommunications, and government services that rely on JavaScript-based serialization libraries may experience operational interruptions. The lack of confidentiality or integrity impact means data breaches are unlikely, but the availability impact can lead to financial losses, reputational damage, and regulatory scrutiny, especially under GDPR requirements for service continuity. Additionally, attackers could leverage this vulnerability as part of a larger attack chain to distract or exhaust resources while attempting other exploits. The vulnerability’s remote exploitability and no requirement for authentication increase the attack surface, making it a priority for incident response and patch management teams in Europe.

CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Exponential Data Expansion (opens in a new tab)
Serialized Data Parameter Blowup (opens in a new tab)
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Jan 2026, 08:44 UTC

WeaknessesCWE-770

Technical details

References

Community reviews

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