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2 vulnerabilities found for protobuf by elixir-protobuf
CVE-2026-104635 (GCVE-0-2026-104635)
Vulnerability from cvelistv5
Published
2026-10-09 08:17
Modified
2026-10-15 15:57
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-674 - Uncontrolled Recursion
Summary
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 type is affected.
In lib/protobuf/json/decode.ex, the embedded-message clause of decode_singular/3 recurses into internal_from_json_data/3 once per nesting level without incrementing or checking the decoder's depth counter. The depth guard increase_depth_and_maybe_throw/1 covers only the Google.Protobuf.ListValue and Google.Protobuf.Struct clauses, so the recursion_limit 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.
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| elixir-protobuf | protobuf |
Version: 0.8.0 ≤ cpe:2.3:a:elixir-protobuf:protobuf:*:*:*:*:*:*:*:* |
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|
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"value": "\u003col\u003e\n\u003cli\u003eDefine and compile a self-referential proto3 message, for example a \u003ccode\u003eTreeNode\u003c/code\u003e message with a single embedded field \u003ccode\u003echild\u003c/code\u003e of type \u003ccode\u003eTreeNode\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eBuild a JSON document that nests the \u003ccode\u003echild\u003c/code\u003e field several thousand levels deep, for example by wrapping \u003ccode\u003e{}\u003c/code\u003e in \u003ccode\u003e{\"child\": ...}\u003c/code\u003e 5,000 times.\u003c/li\u003e\n\u003cli\u003eDecode it with \u003ccode\u003eProtobuf.JSON.decode(json, TreeNode, recursion_limit: 100)\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eObserve that no \u003ccode\u003eProtobuf.JSON.DecodeError\u003c/code\u003e for an exceeded recursion limit is raised and the decoder walks every level. The same depth in a \u003ccode\u003eGoogle.Protobuf.Struct\u003c/code\u003e payload raises \u003ccode\u003e{:recursion_limit_exceeded, 100}\u003c/code\u003e. At larger depths the decoding process consumes hundreds of megabytes and crashes with stack and heap exhaustion.\u003c/li\u003e\n\u003c/ol\u003e"
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"value": "* Define and compile a self-referential proto3 message, for example a TreeNode message with a single embedded field child of type TreeNode.\n* Build a JSON document that nests the child field several thousand levels deep, for example by wrapping {} in {\"child\": ...} 5,000 times.\n* Decode it with Protobuf.JSON.decode(json, TreeNode, recursion_limit: 100).\n* Observe that no Protobuf.JSON.DecodeError for an exceeded recursion limit is raised and the decoder walks every level. The same depth in a Google.Protobuf.Struct payload raises {:recursion_limit_exceeded, 100}. At larger depths the decoding process consumes hundreds of megabytes and crashes with stack and heap exhaustion."
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"value": "\u003cp\u003e\u003cstrong\u003e1. Entry points.\u003c/strong\u003e \u003ccode\u003eProtobuf.JSON.decode/3\u003c/code\u003e, \u003ccode\u003eProtobuf.JSON.decode!/3\u003c/code\u003e, and \u003ccode\u003eProtobuf.JSON.from_decoded/3\u003c/code\u003e in \u003ccode\u003elib/protobuf/json.ex\u003c/code\u003e validate options and call \u003ccode\u003eProtobuf.JSON.Decode.from_json_data/3\u003c/code\u003e, which builds a \u003ccode\u003estate\u003c/code\u003e map carrying \u003ccode\u003edepth: 0\u003c/code\u003e and the \u003ccode\u003erecursion_limit\u003c/code\u003e (default 100). \u003ccode\u003efrom_decoded/3\u003c/code\u003e accepts already-parsed data, so the underlying JSON parser never bounds the depth either.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. Unguarded recursion.\u003c/strong\u003e For a user-defined message module, \u003ccode\u003einternal_from_json_data/3\u003c/code\u003e calls \u003ccode\u003edecode_message/4\u003c/code\u003e, which calls \u003ccode\u003edecode_regular_fields/3\u003c/code\u003e and \u003ccode\u003edecode_oneof_fields/3\u003c/code\u003e. Each field value passes through \u003ccode\u003edecode_value/3\u003c/code\u003e and, for a singular embedded message, reaches the \u003ccode\u003edecode_singular/3\u003c/code\u003e clause matching \u003ccode\u003eembedded?: true\u003c/code\u003e. That clause calls \u003ccode\u003einternal_from_json_data/3\u003c/code\u003e with \u003ccode\u003estate\u003c/code\u003e unchanged, so \u003ccode\u003estate.depth\u003c/code\u003e stays at 0 at every nesting level. Repeated fields and map values reach the same clause through \u003ccode\u003edecode_repeated/3\u003c/code\u003e and \u003ccode\u003edecode_map/3\u003c/code\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. Guard coverage.\u003c/strong\u003e \u003ccode\u003eincrease_depth_and_maybe_throw/1\u003c/code\u003e increments \u003ccode\u003edepth\u003c/code\u003e and throws \u003ccode\u003e{:recursion_limit_exceeded, limit}\u003c/code\u003e when it exceeds the limit. It is called only from the \u003ccode\u003eGoogle.Protobuf.ListValue\u003c/code\u003e and \u003ccode\u003eGoogle.Protobuf.Struct\u003c/code\u003e clauses, which the \u003ccode\u003eGoogle.Protobuf.Value\u003c/code\u003e clause delegates to. The \u003ccode\u003erecursion_limit\u003c/code\u003e documentation scopes the option to those wrappers, and no other path checks depth.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4. Result.\u003c/strong\u003e A self-referential schema such as a \u003ccode\u003eTree\u003c/code\u003e message with a \u003ccode\u003eTree child\u003c/code\u003e 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 \u003ccode\u003emax_heap_size\u003c/code\u003e process flag defaults to unlimited, so repeated or concurrent requests can exhaust the memory of the whole node.\u003c/p\u003e"
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"value": "**1. Entry points.** `Protobuf.JSON.decode/3`, `Protobuf.JSON.decode!/3`, and `Protobuf.JSON.from_decoded/3` in `lib/protobuf/json.ex` validate options and call `Protobuf.JSON.Decode.from_json_data/3`, which builds a `state` map carrying `depth: 0` and the `recursion_limit` (default 100). `from_decoded/3` accepts already-parsed data, so the underlying JSON parser never bounds the depth either.\n\n**2. Unguarded recursion.** For a user-defined message module, `internal_from_json_data/3` calls `decode_message/4`, which calls `decode_regular_fields/3` and `decode_oneof_fields/3`. Each field value passes through `decode_value/3` and, for a singular embedded message, reaches the `decode_singular/3` clause matching `embedded?: true`. That clause calls `internal_from_json_data/3` with `state` unchanged, so `state.depth` stays at 0 at every nesting level. Repeated fields and map values reach the same clause through `decode_repeated/3` and `decode_map/3`.\n\n**3. Guard coverage.** `increase_depth_and_maybe_throw/1` increments `depth` and throws `{:recursion_limit_exceeded, limit}` when it exceeds the limit. It is called only from the `Google.Protobuf.ListValue` and `Google.Protobuf.Struct` clauses, which the `Google.Protobuf.Value` clause delegates to. The `recursion_limit` documentation scopes the option to those wrappers, and no other path checks depth.\n\n**4. Result.** A self-referential schema such as a `Tree` message with a `Tree child` 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 `max_heap_size` process flag defaults to unlimited, so repeated or concurrent requests can exhaust the memory of the whole node."
}
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"value": "1. Entry points. Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, and Protobuf.JSON.from_decoded/3 in lib/protobuf/json.ex validate options and call Protobuf.JSON.Decode.from_json_data/3, which builds a state map carrying depth: 0 and the recursion_limit (default 100). from_decoded/3 accepts already-parsed data, so the underlying JSON parser never bounds the depth either.\n\n2. Unguarded recursion. For a user-defined message module, internal_from_json_data/3 calls decode_message/4, which calls decode_regular_fields/3 and decode_oneof_fields/3. Each field value passes through decode_value/3 and, for a singular embedded message, reaches the decode_singular/3 clause matching embedded?: true. That clause calls internal_from_json_data/3 with state unchanged, so state.depth stays at 0 at every nesting level. Repeated fields and map values reach the same clause through decode_repeated/3 and decode_map/3.\n\n3. Guard coverage. increase_depth_and_maybe_throw/1 increments depth and throws {:recursion_limit_exceeded, limit} when it exceeds the limit. It is called only from the Google.Protobuf.ListValue and Google.Protobuf.Struct clauses, which the Google.Protobuf.Value clause delegates to. The recursion_limit documentation scopes the option to those wrappers, and no other path checks depth.\n\n4. Result. A self-referential schema such as a Tree message with a Tree child 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 max_heap_size process flag defaults to unlimited, so repeated or concurrent requests can exhaust the memory of the whole node."
}
]
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-104635",
"datePublished": "2026-10-09T08:17:52.372Z",
"dateReserved": "2026-10-08T14:45:01.406Z",
"dateUpdated": "2026-10-15T15:57:11.974Z",
"state": "PUBLISHED"
},
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CVE-2026-54451 (GCVE-0-2026-54451)
Vulnerability from cvelistv5
Published
2026-09-17 18:19
Modified
2026-09-21 21:03
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-674 - Uncontrolled Recursion
Summary
Elixir protobuf is a pure Elixir implementation of Google Protobuf. From 0.8.0 until 0.16.1, services that decode attacker-controlled protobuf bytes with Protobuf.Decoder can be taken offline when the schema contains a self-referential or cyclic message type. In lib/protobuf/decoder.ex, Protobuf.Decoder.value_for_field/3 handles an embedded?: true field by recursively entering the decode / build_message / handle_value / value_for_field call chain without enforcing a nesting-depth limit. Deeply nested embedded fields retain non-tail recursive frames, allowing a comparatively small request to consume substantial CPU and memory, pin a BEAM scheduler, and exhaust the node. This issue is fixed in version 0.16.1.
References
| URL | Tags | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||||
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| elixir-protobuf | protobuf |
Version: >= 0.8.0, < 0.16.1 |
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"url": "https://github.com/elixir-protobuf/protobuf/security/advisories/GHSA-rv48-qqj5-crxg"
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}
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"metrics": [
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"title": "Elixir protobuf: Unbounded recursion depth in embedded-message decoding"
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