CVE-2026-42328

The DAG-CBOR and DAG-JSON decoders recurse on each nested map or list without a depth limit. A payload containing deeply nested collections causes the decoder to recurse once per level, growing the goroutine stack until the Go runtime terminates the process with a fatal stack overflow (distinct from a recoverable panic).

For DAG-CBOR, a payload of approximately 2 MB, consisting of repeated 0x81 (array-of-1) bytes followed by a terminator, produces around 2 million recursion frames and reliably exhausts Go's default 1 GB goroutine stack. The existing allocation budget does not prevent this: each nested collection header costs only a handful of budget units, so the stack is exhausted before the budget is. DAG-JSON has equivalent exposure via [[[...]]]-style payloads; it has no budget system and is therefore unprotected against recursion depth as well.

Schema-free decoding (using basicnode.Prototype.Any) allows arbitrary nesting depth. Schema-bound decoding bounds nesting only when the schema itself is non-recursive and contains no fields typed as Any; schemas with recursive type references or any Any-typed fields permit unconstrained nesting at those points.

The fix adds a configurable MaxDepth option to both decoders, defaulting to 1024 nested levels. The decoder returns ErrDecodeDepthExceeded when a payload nests beyond the limit. Well-formed IPLD data rarely approaches this depth in practice; the default is generous for legitimate use while preventing stack exhaustion.

CVE-2026-42328 has a CVSS score of 6.2 (Medium). The vector is requires local access, 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 (0.23.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-42328? CVE-2026-42328 is a medium-severity security vulnerability in github.com/ipld/go-ipld-prime (go), affecting versions < 0.23.0. It is fixed in 0.23.0.
2. How severe is CVE-2026-42328? CVE-2026-42328 has a CVSS score of 6.2 (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 github.com/ipld/go-ipld-prime are affected by CVE-2026-42328? github.com/ipld/go-ipld-prime (go) versions < 0.23.0 is affected.
4. Is there a fix for CVE-2026-42328? Yes. CVE-2026-42328 is fixed in 0.23.0. Upgrade to this version or later.
5. Is CVE-2026-42328 exploitable, and should I be worried? Whether CVE-2026-42328 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-2026-42328 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-2026-42328? Upgrade github.com/ipld/go-ipld-prime to 0.23.0 or later.