{"id":"CVE-2026-80431","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-80431","generatedAt":"2026-10-28T05:26:36.480Z","title":"Out-of-bounds Write in the natural width branch of the text sizing protocol in kitty from 0.40.0 before 0.49.0 allows a program writing to the terminal to write past the end of a fixed-size buffer, because screen_handle_multicell_command() in…","description":"Out-of-bounds Write in the natural width branch of the text sizing protocol in kitty from 0.40.0 before 0.49.0 allows a program writing to the terminal to write past the end of a fixed-size buffer, because screen_handle_multicell_command() in kitty/screen.c appends each codepoint of a grapheme cluster with lc.chars[lc.count++] = ch without any capacity check, while lc is declared by the RAII_ListOfChars macro as a four-element char_type array in the function's stack frame, so an OSC 66 escape code whose payload carries a grapheme cluster longer than four codepoints writes beyond that buffer, one 32-bit value per additional codepoint, in the order the codepoints appear. Where the cluster is preceded in the same payload by a sequence that causes an intermediate flush, the buffer is first migrated to the heap by ensure_space_for_chars() and the write occurs past the heap allocation instead. This results in termination of the kitty process and therefore of all its windows, tabs and child processes.","published":"2026-09-25T14:17:19.000Z","lastModified":"2026-09-29T21:33:00.000Z","status":"Awaiting Analysis","sourceIdentifier":"4daa8cea-433a-44bd-9456-53b127fc289a","cvss":{"version":"4.0","score":6.8,"severity":"MEDIUM","vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-787"],"affected":[],"epss":{"score":0.00134,"percentile":0.02899,"date":"2026-10-27","history":[{"date":"2026-09-26","score":0.00136,"percentile":0.02505}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.13%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-09-25T14:17:19.000Z","detail":{"score":"6.8","severity":"MEDIUM","publishedAt":"2026-09-25T14:17:19.253Z"},"summary":"New CVE, medium severity (CVSS 6.8)."}],"references":[{"url":"https://github.com/kovidgoyal/kitty/commit/7d2fbaadcc2b1eeeef89bd875ec622b42362574b","source":"4daa8cea-433a-44bd-9456-53b127fc289a"},{"url":"https://github.com/kovidgoyal/kitty/releases/tag/v0.49.0","source":"4daa8cea-433a-44bd-9456-53b127fc289a"},{"url":"https://secur0.com/en/cna/cve-list/cve-2026-80431-kitty-text-sizing-out-of-bounds-write","source":"4daa8cea-433a-44bd-9456-53b127fc289a"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80431","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}