CVE-2026-35480 is a medium-severity (CVSS 6.2) CWE-770 vulnerability in github.com/ipld/go-ipld-prime. A fix is available for github.com/ipld/go-ipld-prime — see the affected versions and patch details below.
go-ipld-prime's DAG-CBOR decoder unbounded memory allocation from CBOR headers
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-35480.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/ipld/go-ipld-primeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
The DAG-CBOR decoder uses collection sizes declared in CBOR headers as Go preallocation hints for maps and lists. The decoder does not cap these size hints or account for their cost in its allocation budget, allowing small payloads to cause excessive memory allocation.
A CBOR map or list header can declare an arbitrarily large number of entries, causing the decoder to preallocate proportionally large backing structures before any entries are actually read. Because the allocation budget is only decremented as entries are decoded (not when sizes are declared), this cost is effectively invisible to the budget system. This is compounded by nesting: each level of a nested structure triggers its own unchecked preallocation while consuming minimal budget (one entry per parent level), so a payload under 100 bytes with 10 levels of nesting can cause over 9GB of allocation.
Schema-free decoding (i.e. using basicnode.Prototype.Any) allows arbitrary nesting depth. Schema-bound decoding limits nesting to the schema's structure, but any field typed as Any in the schema permits unconstrained nesting within that field.
The fix caps the preallocation size hint to 1024 entries and decrements the allocation budget when collection sizes are declared. The declared length is still used for entry-count validation, and collections grow dynamically as entries are decoded, so correctly-formed data is unaffected, even beyond the preallocation limit.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/ipld/go-ipld-prime | all versions | 0.22.0go get github.com/ipld/go-ipld-prime@v0.22.0 |
Affected Products
go-ipld-primeprotocolDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ipld/go-ipld-prime, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/ipld/go-ipld-prime to 0.22.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35480 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2026-35480 in your dependencies?
Find it across Go, including transitive dependencies.