CVE-2026-104635
Uncontrolled Recursion
Published Oct 9, 2026 · corrected/updated Oct 15, 2026 · evidence confidence high
## Summary Uncontrolled Recursion vulnerability in in elixir-protobuf protobuf allows an unauthenticated remote attacker to crash the decoding process via a deeply nested JSON document. Any application that decodes attacker-supplied JSON with , , or into a schema that contains a self-referential or cyclic message type is affected. In , the embedded-message clause of recurses into once per nesting level without incrementing or checking the decoder's depth counter. The depth guard covers only the and clauses, so the option has no effect on user-defined message types. Each nesting level allocates a stack frame and heap objects, and a sufficiently deep document exhausts the memory of the decoding process. Confidentiality and integrity are not affected. This issue affects protobuf: from 0.8.0 before 0.17.1. ## Details **1. Entry points.** , , and in validate options and call , which builds a map carrying and the (default 100). accepts already-parsed data, so the underlying JSON parser never bounds the depth either. **2. Unguarded recursion.** For a user-defined message module, calls , which calls and . Each field value passes through and, for a singular embedded message, reaches the clause matching . That clause calls with unchanged, so stays at 0 at every nesting level. Repeated fields and map values reach the same clause through and . **3. Guard coverage.** increments and throws when it exceeds the limit. It is called only from the and clauses, which the clause delegates to. The documentation scopes the option to those wrappers, and no other path checks depth. **4. Result.** A self-referential schema such as a message with a field recurses once per JSON nesting level with no bound. Each level holds a live stack frame and allocates heap objects, so a sufficiently deep document exhausts the memory of the decoding process and crashes it. The BEAM process flag defaults to unlimited, so repeated or concurrent requests can exhaust the memory of the whole node. ## Proof of co
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2026-104635 is a high public vulnerability record for this product. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether this product is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: protobuf (0.8.0 → 0.17.1); protobuf. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 8.2, EPSS 0.4%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-674. Sources contributing to this record: cve_org, epss, github, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in the CISA KEV catalog.
Patch and remediation
No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Oct 9, 2026 · GitHub Advisory Database
Fix available
protobuf fixed in 0.17.1
Oct 14, 2026 · Snyk Vulnerability Database
Detected
Uncontrolled Recursion
Oct 15, 2026 · GitHub Advisory Database
Fix available
protobuf fixed in 0.17.1
Oct 15, 2026 · NIST NVD
Updated
Uncontrolled Recursion vulnerability in Protobuf.JSON.Decode in elixir-protobuf protobuf allows an unauthenticated remote attacker to crash the decoding process via a deeply nested JSON document. Any application that decodes attacker-supplied JSON with Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, or Protobuf.JSON.from_decoded/3 into a schema that contains a self-referential or cyclic message t
Affected
- Hex protobuf0.8.0 → 0.17.1
- hex protobufversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2026-104635
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-104635
30-day exploitation probability 0.4%
first.org - GitHub Advisory DatabasePackage advisoryGHSA-m497-c2h9-rvw6
GitHub Advisory Database record mirrored by OSV.
github.com - NIST NVDVulnerability recordCVE-2026-104635
Uncontrolled Recursion vulnerability in Protobuf.JSON.Decode in elixir-protobuf protobuf allows an unauthenticated remote attacker to crash the decoding process via a deeply nested JSON document. Any application that decodes attacker-supplied JSON with Protobuf.JSON.decode/3, Pro
nvd.nist.gov - OSV.devPackage advisoryEEF-CVE-2026-104635
Uncontrolled recursion in elixir-protobuf/protobuf JSON decoding of self-referential messages
osv.dev - Snyk Vulnerability DatabasePackage advisorySNYK-HEX-PROTOBUF-20828185
Uncontrolled Recursion
security.snyk.io