Summary
@stablelib/cbor: Stack exhaustion Denial of Service via deeply nested CBOR arrays, maps, or tags
@stablelib/cbor decodes nested CBOR structures recursively and does not enforce a maximum nesting depth. A sufficiently deep attacker-controlled CBOR payload can therefore crash decoding with RangeError: Maximum call stack size exceeded.
Details
The decoder processes arrays, maps, and tagged values through recursive calls. Each nested container causes another descent into _decodeValue() until a leaf value is reached.
There is no depth limit, no iterative fallback, and no protection against pathological nesting. An attacker can therefore supply a payload made of thousands of nested arrays, maps, or tags and force the decoder to recurse until the JavaScript call stack is exhausted.
PoC
import { decode } from "@stablelib/cbor";
const depth = 12000;
const payload = new Uint8Array(depth + 1);
// Build [[[...[null]...]]]
payload.fill(0x81, 0, depth); // array(1)
payload[depth] = 0xf6; // null
decode(payload);
// RangeError: Maximum call stack size exceeded
Impact
Any application that decodes attacker-controlled CBOR can be forced into a reliable denial of service with a single crafted payload.
The immediate result is an exception during decoding. In services that do not catch that exception safely, the request fails and the worker or process handling the decode may terminate.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Upgrade to version 2.0.4. The stack is limited to 128 by default, but can be configured using the maxDepth option. Catch the CBORMaxDepthExceededError exception.
Frequently Asked Questions
- What is GHSA-5JG4-P4QW-CGFR? GHSA-5JG4-P4QW-CGFR is a high-severity security vulnerability in @stablelib/cbor (npm), affecting versions < 2.0.3. It is fixed in 2.0.3.
- Which versions of @stablelib/cbor are affected by GHSA-5JG4-P4QW-CGFR? @stablelib/cbor (npm) versions < 2.0.3 is affected.
- Is there a fix for GHSA-5JG4-P4QW-CGFR? Yes. GHSA-5JG4-P4QW-CGFR is fixed in 2.0.3. Upgrade to this version or later.
- Is GHSA-5JG4-P4QW-CGFR exploitable, and should I be worried? Whether GHSA-5JG4-P4QW-CGFR 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
- What actually determines whether GHSA-5JG4-P4QW-CGFR 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.
- How do I fix GHSA-5JG4-P4QW-CGFR? Upgrade
@stablelib/cborto 2.0.3 or later.