Integer Overflow or Wraparound in NATS Server

Answer in brief

CVE-2019-13126 records a High severity (CVSS 7.5) vulnerability in Integer Overflow or Wraparound in NATS Server. The current sources do not mark it as known exploited. The current feed maps github.com/nats-io/nats-server/v2 (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published May 18, 2021Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps github.com/nats-io/nats-server/v2 (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
github.com/nats-io/nats-server/v2go	>=0 <2.2.0	2.2.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for github.com/nats-io/nats-server/v2.
Review the reported fix. Update github.com/nats-io/nats-server/v2 to 2.2.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
May 18, 2021
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

An integer overflow in NATS Server before 2.2.0 allows a remote attacker to crash the server by sending a crafted request. ### Specific Go Packages Affected github.com/nats-io/nats-server/v2/server

Quoted source text, attributed separately from HOL analysis.