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ProbeLabs23 findings · 123 requirementsThe fastest JSON parser for Go — formally verified with ReqProof (real library, master).
Delete left dangling trailing comma on array/object element followed by whitespace+comma
This defect has been fixed and verified.
Introduced
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Change history
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What this means for you
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`Delete` (parser.go:864) produced malformed JSON output (rejected by `encoding/json.Unmarshal`) whenever the deleted element was followed by one or more JSON whitespace bytes (space, tab, LF, CR) and then a comma or the container close bracket. The dangling-byte sequences were: * `Delete("[0,0 ]", "[1]")` -> `[0, ]` (trailing comma before `]`) * `Delete("[0,0 ,0]", "[1]")` -> `[0, ,0]` (dangling comma between spaces) * `Delete("[0,0\n,0]", "[1]")` -> `[0,\n,0]` (newline variant) * `Delete("[0,0 ,0]", "[1]")` -> `[0, ,0]` (multi-space variant) Root cause was two-fold: 1. The array-branch cleanup (parser.go:932-938, `data[idx] == ']'` case) only advanced `keyOffset` to `tokStart`; it did not handle the whitespace-before-`]` shape, so the cleanup block ran with the wrong `endOffset` and left the comma. 2. The array-branch whitespace-then-comma case was missing entirely. The object-branch (parser.go:907-916) had `data[idx] == ' ' && data[nextIdx] == ','`, but (a) it only matched a SINGLE 0x20 space, missing `\t`, `\n`, `\r`, and multi-byte whitespace runs, and (b) the symmetric case was absent from the array branch. 3. The final cleanup (parser.go:948) only checked `remainedValue[i] == '}'` (object close), so deleting the LAST array element left the comma dangling before `]`. Hazard class: silent malformed-JSON output on caller-controlled input shape (whitespace placement is arbitrary in JSON). Found by FuzzPathMutation during the final hazard sweep.
Severity, explained
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- risk area
- Data Integrity
Root cause
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Disposition: Covered by a requirement
Proof it's fixed
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Covered by a requirement.
- Malformed Input on SYS-REQ-010
Blast radius
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Nothing to trace into
This finding links no requirements, so there is no dependency graph to follow. Everything we know about it is in the evidence above.
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