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ProbeLabs23 findings · 123 requirementsThe fastest JSON parser for Go — formally verified with ReqProof (real library, master).
ParseInt("-") returns (0, nil) — silent false-success on sign-only input
This defect has been fixed and verified.
Introduced
When and where this issue first entered the codebase — the commit it traces back to, and the audit run that first flagged it.
Change history
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What this means for you
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`ParseInt` (parser.go:1498) delegates to `parseInt` (bytes.go:9). When the input is exactly a sign byte with no following digits (`"-"` or `"+"`-style input where `+` is rejected because it isn't valid JSON but `-` is a valid JSON number prefix), the parser: 1. strips the leading `-` (bytes.go:15-18), leaving an empty byte slice; 2. iterates over the empty slice (zero iterations), so `n` stays `0`; 3. falls through to the `if neg` branch (bytes.go:43) and returns `(-0, true, false)` = `(0, nil)`. The caller (`GetInt` / any code using `ParseInt` to validate a JSON number token) is told the input parsed successfully with value `0`. This is silent false-success on caller-controlled input: a JSON value of just `-` is malformed (no digits follow the sign) but is reported as a well-formed integer equal to zero. Hazard class: this is the same family as the JSON fuzzer's existing `ParseInt` finding — the input partition "sign byte only, no digits" is not covered by the parser's malformed-input branch. The catalog obligation `malformed_input` requires a typed error on this partition; the code returns `(0, nil)` instead.
Severity, explained
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- risk area
- Error Handling
Root cause
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Disposition: Covered by a known issue
Proof it's fixed
The tests, tightened requirements and new obligations that prove this defect is gone — and can't quietly return.
Covered by a known issue.
- Malformed Input on SYS-REQ-015
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.
Discussions
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