{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "source": "REFERENCES"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7d2fbaadcc2b1eeeef89bd875ec622b42362574b"
            },
            {
              "fixed": "07ed6aa3de28af2a01e521f18c56ed292aa34cfc"
            }
          ],
          "repo": "https://github.com/kovidgoyal/kitty",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Secur0",
    "cwe_ids": [
      "CWE-787"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80431.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "0.40.0"
          },
          {
            "fixed": "0.49.0"
          }
        ],
        "source": "AFFECTED_FIELD"
      },
      {
        "extracted_events": [
          {
            "introduced": "0.40.0"
          },
          {
            "fixed": "0.49.0"
          }
        ],
        "source": "CPE_FIELD"
      },
      {
        "extracted_events": [
          {
            "introduced": "0.40.0"
          },
          {
            "fixed": "0.49.0"
          }
        ],
        "source": "DESCRIPTION"
      }
    ]
  },
  "details": "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.",
  "id": "CVE-2026-80431",
  "modified": "2026-09-27T03:30:50.017322947Z",
  "published": "2026-09-25T13:23:51.590Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80431.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/kovidgoyal/kitty/releases/tag/v0.49.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80431"
    },
    {
      "type": "ADVISORY",
      "url": "https://secur0.com/en/cna/cve-list/cve-2026-80431-kitty-text-sizing-out-of-bounds-write"
    },
    {
      "type": "FIX",
      "url": "https://github.com/kovidgoyal/kitty/commit/7d2fbaadcc2b1eeeef89bd875ec622b42362574b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/kovidgoyal/kitty"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Out-of-bounds write in the kitty text sizing protocol allows termination of the terminal process"
}