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Fix byte lookup when decoding length of RLP structure #6051

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Merged
Amxx merged 2 commits into from
Nov 10, 2025
Merged

Fix byte lookup when decoding length of RLP structure #6051

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Fix byte lookup when decoding length of RLP structure
Amxx Nov 4, 2025
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Amxx Nov 4, 2025
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5 changes: 5 additions & 0 deletions .changeset/yellow-clowns-mate.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'openzeppelin-solidity': patch
---

`RLP`: Fix RLP encoding validity check when decoding long lists or strings
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@ernestognw ernestognw Nov 4, 2025

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Maybe include in a ### Bug fixes section of the changelog?

11 changes: 6 additions & 5 deletions contracts/utils/RLP.sol
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Expand Up @@ -351,9 +351,10 @@ library RLP {
// Case: Long string (>55 bytes)
uint256 lengthLength = prefix - SHORT_OFFSET - SHORT_THRESHOLD;

require(itemLength > lengthLength && bytes1(item.load(0)) != 0x00, RLPInvalidEncoding());
bytes32 lenChunk = item.load(1);
require(itemLength > lengthLength && bytes1(lenChunk) != 0x00, RLPInvalidEncoding());

uint256 len = uint256(item.load(1)) >> (256 - 8 * lengthLength);
uint256 len = uint256(lenChunk) >> (256 - 8 * lengthLength);
require(len > SHORT_THRESHOLD && itemLength > lengthLength + len, RLPInvalidEncoding());

return (lengthLength + 1, len, ItemType.Data);
Expand All @@ -369,10 +370,10 @@ library RLP {
// Case: Long list
uint256 lengthLength = prefix - LONG_OFFSET - SHORT_THRESHOLD;

require(itemLength > lengthLength, RLPInvalidEncoding());
require(bytes1(item.load(0)) != 0x00);
bytes32 lenChunk = item.load(1);
require(itemLength > lengthLength && bytes1(lenChunk) != 0x00, RLPInvalidEncoding());

uint256 len = uint256(item.load(1)) >> (256 - 8 * lengthLength);
uint256 len = uint256(lenChunk) >> (256 - 8 * lengthLength);
require(len > SHORT_THRESHOLD && itemLength > lengthLength + len, RLPInvalidEncoding());

return (lengthLength + 1, len, ItemType.List);
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