{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-80431", "assignerOrgId": "4daa8cea-433a-44bd-9456-53b127fc289a", "state": "PUBLISHED", "assignerShortName": "Secur0", "dateReserved": "2026-08-26T10:49:01.410Z", "datePublished": "2026-09-25T13:23:51.590Z", "dateUpdated": "2026-09-25T13:23:51.590Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "4daa8cea-433a-44bd-9456-53b127fc289a", "shortName": "Secur0", "dateUpdated": "2026-09-25T13:23:51.590Z"}, "title": "Out-of-bounds write in the kitty text sizing protocol allows termination of the terminal process", "datePublic": "2026-09-21T04:01:00.000Z", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-787", "description": "CWE-787 Out-of-bounds Write", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-100", "descriptions": [{"lang": "en", "value": "CAPEC-100 Overflow Buffers"}]}], "affected": [{"vendor": "Kovid Goyal", "product": "kitty", "repo": "https://github.com/kovidgoyal/kitty", "programFiles": ["kitty/screen.c"], "versions": [{"status": "affected", "version": "0.40.0", "lessThan": "0.49.0", "versionType": "semver"}], "defaultStatus": "unaffected"}], "cpeApplicability": [{"operator": "OR", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:kovidgoyal:kitty:*:*:*:*:*:*:*:*", "versionStartIncluding": "0.40.0", "versionEndExcluding": "0.49.0"}]}]}], "descriptions": [{"lang": "en", "value": "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.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "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 <code>screen_handle_multicell_command()</code> in <code>kitty/screen.c</code> appends each codepoint of a grapheme cluster with <code>lc.chars[lc.count++] = ch</code> without any capacity check, while <code>lc</code> is declared by the <code>RAII_ListOfChars</code> macro as a four-element <code>char_type</code> 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 <code>ensure_space_for_chars()</code> 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."}]}], "tags": ["x_open-source"], "references": [{"url": "https://github.com/kovidgoyal/kitty/commit/7d2fbaadcc2b1eeeef89bd875ec622b42362574b", "tags": ["patch"]}, {"url": "https://github.com/kovidgoyal/kitty/releases/tag/v0.49.0", "tags": ["release-notes"]}, {"url": "https://secur0.com/en/cna/cve-list/cve-2026-80431-kitty-text-sizing-out-of-bounds-write", "tags": ["third-party-advisory", "technical-description"]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "MEDIUM", "baseScore": 6.8, "vectorString": "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"}}], "solutions": [{"lang": "en", "value": "Upgrade to kitty 0.49.0 or later.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "Upgrade to kitty 0.49.0 or later."}]}], "credits": [{"lang": "en", "value": "C4sh3R", "type": "finder"}, {"lang": "en", "value": "Cristian Fern\u00e1ndez Cornejo", "type": "analyst"}, {"lang": "en", "value": "Xo\u00e1n M. Otero Jorge", "type": "analyst"}, {"lang": "en", "value": "Secur0 CNA", "type": "coordinator"}, {"lang": "en", "value": "Kovid Goyal", "type": "remediation developer"}], "source": {"discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.5"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "kitty", "programFiles": ["kitty/screen.c"], "repo": "https://github.com/kovidgoyal/kitty", "vendor": "Kovid Goyal", "versions": [{"lessThan": "0.49.0", "status": "affected", "version": "0.40.0", "versionType": "semver"}]}], "source": "4daa8cea-433a-44bd-9456-53b127fc289a"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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", "lastModified": "2026-09-25T14:17:19.253", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "LOCAL", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.8, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "4daa8cea-433a-44bd-9456-53b127fc289a", "type": "Secondary"}]}, "published": "2026-09-25T14:17:19.253", "references": [{"source": "4daa8cea-433a-44bd-9456-53b127fc289a", "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"}], "sourceIdentifier": "4daa8cea-433a-44bd-9456-53b127fc289a", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-787"}], "source": "4daa8cea-433a-44bd-9456-53b127fc289a", "type": "Secondary"}]}

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