CVE-2026-41907

The v3(), v5(), and v6() API methods (not uuid release versions) accept external output buffers but do not reject out-of-range writes (small buf or large offset).
By contrast, v4(), v1(), and v7() API methods explicitly throw RangeError on invalid bounds.

This inconsistency allows silent partial writes into caller-provided buffers.

Affected code

• src/v35.ts (v3()/v5() path) writes buf[offset + i] without bounds validation.
• src/v6.ts writes buf[offset + i] without bounds validation.

Reproducible PoC

cd /home/StrawHat/uuid
npm ci
npm run build

node --input-type=module -e "
import {v4,v5,v6} from './dist-node/index.js';
const ns='6ba7b810-9dad-11d1-80b4-00c04fd430c8';
for (const [name,fn] of [
  ['v4()',()=>v4({},new Uint8Array(8),4)],
  ['v5()',()=>v5('x',ns,new Uint8Array(8),4)],
  ['v6()',()=>v6({},new Uint8Array(8),4)],
]) {
  try { fn(); console.log(name,'NO_THROW'); }
  catch(e){ console.log(name,'THREW',e.name); }
}"

Observed:

• v4() THREW RangeError
• v5() NO_THROW
• v6() NO_THROW

Example partial overwrite evidence captured during audit:

same true buf [
  170, 170, 170, 170,
   75, 224, 100,  63
]
v6 [
  187, 187, 187, 187,
   31,  19, 185,  64
]

Security impact

• Primary: integrity/robustness issue (silent partial output).
• If an application assumes full UUID writes into preallocated buffers, this can produce malformed/truncated/partially stale identifiers without error.
• In systems where caller-controlled offsets/buffer sizes are exposed indirectly, this may become a security-relevant logic flaw.

A write operation targets a memory location beyond the intended buffer boundary. Typical impact: memory corruption, crash, or arbitrary code execution.

CVE-2026-41907 has a CVSS score of 7.5 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (12.0.1, 13.0.1, 11.1.1); upgrading removes the vulnerable code path.

Kodem intelligence

Add the same guard used by v4()/v1()/v7():

if (offset < 0 || offset + 16 > buf.length) {
  throw new RangeError(`UUID byte range ${offset}:${offset + 15} is out of buffer bounds`);
}

Apply to:

• src/v35.ts (covers v3() and v5())
• src/v6.ts

1. What is CVE-2026-41907? CVE-2026-41907 is a medium-severity out-of-bounds write vulnerability in uuid (npm), affecting versions >= 12.0.0, < 12.0.1. It is fixed in 12.0.1, 13.0.1, 11.1.1. A write operation targets a memory location beyond the intended buffer boundary.
2. How severe is CVE-2026-41907? CVE-2026-41907 has a CVSS score of 7.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of uuid are affected by CVE-2026-41907? uuid (npm) versions >= 12.0.0, < 12.0.1 is affected.
4. Is there a fix for CVE-2026-41907? Yes. CVE-2026-41907 is fixed in 12.0.1, 13.0.1, 11.1.1. Upgrade to this version or later.
5. Is CVE-2026-41907 exploitable, and should I be worried? Whether CVE-2026-41907 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-41907 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-41907?
   • Upgrade uuid to 12.0.1 or later
   • Upgrade uuid to 13.0.1 or later
   • Upgrade uuid to 11.1.1 or later