json-smart through 2.6.0 Strict-Mode Validation Bypass via 0x1A Character

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

json-smart through 2.6.0 contains an input validation bypass vulnerability that allows attackers to evade strict-mode trailing-data checks by inserting a literal 0x1A character. Attackers can append 0x1A and malformed content to pass JSONValue.parseStrict or isValidJsonStrict validation, creating parser differentials with downstream parsers like Jackson or Gson.

Source published

20 Oct 2026 15:40:29 UTC

Source modified

20 Oct 2026 16:30:53 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N