Analysis Run

{"no_findings":false,"summary":"Bytecode matches a BeaconProxy-style fallback: it loads the EIP-1967 beacon slot, STATICCALLs the beacon, then DELEGATECALLs to the returned implementation. Selector inference is unavailable and beacon access control is not visible from this bytecode, so trust assumptions are uncertain.","findings":[{"severity":"medium","category":"upgradeability","title":"Beacon proxy delegates to implementation supplied by external beacon (trust/upgrade risk)","exploit_scenario":"The fallback path always DELEGATECALLs to an implementation address returned by an external beacon. If the beacon contract can be upgraded by an attacker (or if the beacon slot is altered via storage collision in the delegated implementation), the attacker can point the beacon to a malicious implementation and gain full control of the proxy’s storage and assets. This hinges on beacon governance, which cannot be verified from bytecode alone.","recommendation":"Treat the beacon as a critical trust boundary: ensure the beacon’s upgrade mechanism is tightly access-controlled (e.g., multisig/timelock) and monitor implementation changes. Consider additional validation (e.g., codehash checks or allowlists) if immutability is desired.","evidence":"SLOAD of slot 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50 at pc 57 feeds a STATICCALL to the beacon (pc 59), and the returned address is used as the DELEGATECALL target (pc 64). Detector confirms target varies.","locations":["pc:0x39","pc:0x3b","pc:0x40"]}]}

OpenAI Codex v0.77.0 (research preview)
--------
workdir: /tmp/codex-c97dqay3
model: gpt-5.2-codex
provider: openai
approval: never
sandbox: read-only
reasoning effort: xhigh
reasoning summaries: auto
session id: 019ba8fe-5487-7c93-aecc-5636c29ce61c
--------
user
You are a security auditor. You ONLY have runtime bytecode + analysis artifacts.
You MUST read `BYTECODE_BUNDLE.json` before concluding; it contains the bytecode summary,
evidence bundle, callsites, storage slots, and detector findings.

Special cases when reasoning from bytecode (be explicit about uncertainty):
- Selector inference is best-effort; missing selectors are common.
- Fallback/receive paths may be the only entrypoints.
- CALL vs DELEGATECALL semantics differ; DELEGATECALL executes in caller storage.
- Proxy patterns (EIP-1967, minimal proxies, beacon) change which storage is authoritative.
- Storage slots are raw; mappings/arrays appear via keccak patterns, names are unknown.
- Guard detection is heuristic; absence of guards does NOT mean unguarded.
- Returndata checking is unknown unless explicitly shown in evidence.
- Precompiles (0x1..0x9) and common ERC20 transfer selectors may appear; do not over-claim.

Output MUST be valid JSON matching the provided schema.
- If you find nothing meaningful: set no_findings=true and findings=[].
- Otherwise: set no_findings=false and include findings with severity/category/title.
- Locations can be pc references like "pc:0x123" or selectors like "selector:0xa9059cbb".

Focus on: reentrancy, access control, upgradeability/proxy issues, signature validation,
accounting/invariant breaks, dangerous delegatecall, and untrusted external calls.
Be conservative: if evidence is weak, mark severity low/medium and explain why.
mcp startup: no servers

thinking
**Preparing to read BYTECODE_BUNDLE.json**
exec
/bin/bash -lc ls in /tmp/codex-c97dqay3 succeeded in 6ms:
BYTECODE_BUNDLE.json
codex-output-schema.json
exec
/bin/bash -lc 'cat BYTECODE_BUNDLE.json' in /tmp/codex-c97dqay3 succeeded in 13ms:
{
  "analysis_artifact": {
    "address": "0xf5b9f07d0a1fd110dacc7ab247fbc82ff5cbc25e",
    "artifact_hash": "0xe9fcacb094026d43fe212e5ebe76a2ee9525c44187f729722caf1d4369a74838",
    "artifact_json": {
      "auth": {
        "guards": []
      },
      "basic_blocks": [
        {
          "end_pc": 72,
          "hash": "0x62f80a1953928341faf45540fbdeb4ce6071d28a7a7f514c40706ded42695b72",
          "opcodes": [
            "CALLDATASIZE",
            "RETURNDATASIZE",
            "RETURNDATASIZE",
            "CALLDATACOPY",
            "RETURNDATASIZE",
            "RETURNDATASIZE",
            "CALLDATASIZE",


thinking
**Analyzing beacon proxy upgradeability risks**

I'm unpacking the bytecode of a beacon proxy pattern, focusing on how it loads the beacon address from storage, does a staticcall to fetch the implementation, then delegates calls there. The main concern is that the delegatecall target depends entirely on the external beacon contract, so if that beacon or the storage slot is compromised or mutable without tight access control, it could let attackers execute arbitrary code through the proxy. I'm also noting the staticcall success isn't validated before delegatecall, but that likely just leads to a revert, which is normal. I'll prepare a clear JSON report capturing the medium-severity upgradeability risk, evidence code locations, and highlight the importance of beacon trust and access controls.
thinking
**Summarizing beacon proxy fallback behavior**

I'm refining the analysis to highlight that the bytecode only includes a fallback function which performs a staticcall to the beacon slot and delegates calls to the returned implementation. The staticcall success isn't explicitly checked but a failed call leads to delegatecall reverting safely. The summary will mention the reliance on beacon trust and upgrade controls, which aren't visible from bytecode alone, and that selector inference isn't possible since only fallback is present. I'll reflect these points clearly in the JSON output.
codex
{"no_findings":false,"summary":"Bytecode matches a BeaconProxy-style fallback: it loads the EIP-1967 beacon slot, STATICCALLs the beacon, then DELEGATECALLs to the returned implementation. Selector inference is unavailable and beacon access control is not visible from this bytecode, so trust assumptions are uncertain.","findings":[{"severity":"medium","category":"upgradeability","title":"Beacon proxy delegates to implementation supplied by external beacon (trust/upgrade risk)","exploit_scenario":"The fallback path always DELEGATECALLs to an implementation address returned by an external beacon. If the beacon contract can be upgraded by an attacker (or if the beacon slot is altered via storage collision in the delegated implementation), the attacker can point the beacon to a malicious implementation and gain full control of the proxy’s storage and assets. This hinges on beacon governance, which cannot be verified from bytecode alone.","recommendation":"Treat the beacon as a critical trust boundary: ensure the beacon’s upgrade mechanism is tightly access-controlled (e.g., multisig/timelock) and monitor implementation changes. Consider additional validation (e.g., codehash checks or allowlists) if immutability is desired.","evidence":"SLOAD of slot 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50 at pc 57 feeds a STATICCALL to the beacon (pc 59), and the returned address is used as the DELEGATECALL target (pc 64). Detector confirms target varies.","locations":["pc:0x39","pc:0x3b","pc:0x40"]}]}
tokens used
17,876

{
    "codex": {
        "ran_at": "2026-01-10T17:41:41.933090+00:00",
        "returncode": 0
    },
    "project": {
        "mode": "bytecode",
        "bytecode_length": 166,
        "bytecode_truncated": false,
        "capability_graph_present": true,
        "analysis_artifact_present": true
    },
    "summary": "Bytecode matches a BeaconProxy-style fallback: it loads the EIP-1967 beacon slot, STATICCALLs the beacon, then DELEGATECALLs to the returned implementation. Selector inference is unavailable and beacon access control is not visible from this bytecode, so trust assumptions are uncertain.",
    "raw_final": {
        "summary": "Bytecode matches a BeaconProxy-style fallback: it loads the EIP-1967 beacon slot, STATICCALLs the beacon, then DELEGATECALLs to the returned implementation. Selector inference is unavailable and beacon access control is not visible from this bytecode, so trust assumptions are uncertain.",
        "findings": [
            {
                "title": "Beacon proxy delegates to implementation supplied by external beacon (trust/upgrade risk)",
                "category": "upgradeability",
                "evidence": "SLOAD of slot 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50 at pc 57 feeds a STATICCALL to the beacon (pc 59), and the returned address is used as the DELEGATECALL target (pc 64). Detector confirms target varies.",
                "severity": "medium",
                "locations": [
                    "pc:0x39",
                    "pc:0x3b",
                    "pc:0x40"
                ],
                "recommendation": "Treat the beacon as a critical trust boundary: ensure the beacon\u2019s upgrade mechanism is tightly access-controlled (e.g., multisig/timelock) and monitor implementation changes. Consider additional validation (e.g., codehash checks or allowlists) if immutability is desired.",
                "exploit_scenario": "The fallback path always DELEGATECALLs to an implementation address returned by an external beacon. If the beacon contract can be upgraded by an attacker (or if the beacon slot is altered via storage collision in the delegated implementation), the attacker can point the beacon to a malicious implementation and gain full control of the proxy\u2019s storage and assets. This hinges on beacon governance, which cannot be verified from bytecode alone."
            }
        ],
        "no_findings": false
    },
    "no_findings": false,
    "schema_version": 1
}

00000000: CALLDATASIZE
00000001: RETURNDATASIZE
00000002: RETURNDATASIZE
00000003: CALLDATACOPY
00000004: RETURNDATASIZE
00000005: RETURNDATASIZE
00000006: CALLDATASIZE
00000007: RETURNDATASIZE
00000008: PUSH1 0x20
0000000a: CALLDATASIZE
0000000b: PUSH1 0x04
0000000d: CALLDATASIZE
0000000e: PUSH4 0x5c60da1b
00000013: PUSH1 0xe0
00000015: SHL
00000016: CALLDATASIZE
00000017: MSTORE
00000018: PUSH32 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50
00000039: SLOAD
0000003a: GAS
0000003b: STATICCALL
0000003c: POP
0000003d: CALLDATASIZE
0000003e: MLOAD
0000003f: GAS
00000040: DELEGATECALL
00000041: RETURNDATASIZE
00000042: PUSH1 0x00
00000044: DUP1
00000045: RETURNDATACOPY
00000046: PUSH1 0x4d
00000048: JUMPI
00000049: RETURNDATASIZE
0000004a: PUSH1 0x00
0000004c: REVERT
0000004d: JUMPDEST
0000004e: RETURNDATASIZE
0000004f: PUSH1 0x00
00000051: RETURN