{"id":"CVE-2026-88355","title":"An incorrect buffer size calculation vulnerability exists in tinyexpr commit 4a7456e in new_expr()","summary":"An incorrect buffer size calculation vulnerability exists in tinyexpr commit 4a7456e in new_expr(). For arity-0 expression nodes, including constants, variables, and zero-argument functions, the function allocates less memory than sizeof…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-131"],"published":"2026-09-24","updated":"2026-10-06","sourceUpdated":"2026-10-06T18:16:57.013","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-88355","references":[{"url":"https://github.com/codeplea/tinyexpr/issues/145","label":"cve@mitre.org"},{"url":"https://github.com/szaydel/tinyexpr/commit/fe7459728c2ab8d2f91365abe56601cdd0e24f9b","label":"cve@mitre.org"},{"url":"https://github.com/codeplea/tinyexpr/issues/145","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","cve.org","exploit-available"],"epss":0.00415,"epssPercentile":0.3561,"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-06T15:44:34.584065Z"},"ingestedAt":"2026-09-24T15:45:56.663Z","slug":"CVE-2026-88355","body":"## Overview\n\nAn incorrect buffer size calculation vulnerability exists in tinyexpr commit 4a7456e in new_expr(). For arity-0 expression nodes, including constants, variables, and zero-argument functions, the function allocates less memory than sizeof(te_expr) but treats the returned allocation as a complete te_expr object. This results in undefined behavior and can cause deterministic process termination in UBSan-instrumented builds.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":53,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":216635,"id":"CVE-2026-88355","ts":1791310380653,"field":"exploit_available","old":"false","new":"true"},{"seq":216634,"id":"CVE-2026-88355","ts":1791310380653,"field":"cvss","old":null,"new":"7.5"},{"seq":216633,"id":"CVE-2026-88355","ts":1791310380653,"field":"severity","old":"none","new":"high"}]}