Vulnerability-Lookup

CVE-2026-80431 (GCVE-0-2026-80431)

Vulnerability from cvelistv5 – Published: 2026-09-25 13:23 – Updated: 2026-09-25 15:07 X_Open Source

Title

Out-of-bounds write in the kitty text sizing protocol allows termination of the terminal process

Summary

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.

Severity

6.8 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-25 15:05 UTC

CWE

CWE-787 - Out-of-bounds Write

Assigner

Secur0 INCIBE root

References

3 references

URL	Tags
https://github.com/kovidgoyal/kitty/commit/7d2fba…	patch
https://github.com/kovidgoyal/kitty/releases/tag/…	release-notes
https://secur0.com/en/cna/cve-list/cve-2026-80431…	third-party-advisorytechnical-description

Impacted products

1 product

Vendor	Product	Version	CPE status
Kovid Goyal	kitty	Affected: 0.40.0 , < 0.49.0 (semver) cpe:2.3:a:kovidgoyal:kitty::::::::

Date Public

2026-09-21 04:01

Credits

C4sh3R Cristian Fernández Cornejo Xoán M. Otero Jorge Secur0 CNA Kovid Goyal

Show details on NVD website

JSON

To clipboard

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}

FKIE_CVE-2026-80431

Vulnerability from fkie_nvd - Published: 2026-09-25 14:17 - Updated: 2026-09-25 16:17

Severity

6.8 (Medium) - 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

Summary

References

	URL	Tags
	4daa8cea-433a-44bd-9456-53b127fc289a	https://github.com/kovidgoyal/kitty/commit/7d2fbaadcc2b1eeeef89bd875ec622b42362574b
	4daa8cea-433a-44bd-9456-53b127fc289a	https://github.com/kovidgoyal/kitty/releases/tag/v0.49.0
	4daa8cea-433a-44bd-9456-53b127fc289a	https://secur0.com/en/cna/cve-list/cve-2026-80431-kitty-text-sizing-out-of-bounds-write

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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    }
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    {
      "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"
    }
  ]
}

GHSA-FX7R-Q727-J825

Vulnerability from github – Published: 2026-09-25 15:31 – Updated: 2026-09-25 15:31

Details

Severity

6.8 (Medium)


                  
                    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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80431"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-787"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-25T14:17:19Z",
    "severity": "MODERATE"
  },
  "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\u0027s 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": "GHSA-fx7r-q727-j825",
  "modified": "2026-09-25T15:31:47Z",
  "published": "2026-09-25T15:31:47Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80431"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kovidgoyal/kitty/commit/7d2fbaadcc2b1eeeef89bd875ec622b42362574b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kovidgoyal/kitty/releases/tag/v0.49.0"
    },
    {
      "type": "WEB",
      "url": "https://secur0.com/en/cna/cve-list/cve-2026-80431-kitty-text-sizing-out-of-bounds-write"
    }
  ],
  "schema_version": "1.4.0",
  "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/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",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
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Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-80431 (GCVE-0-2026-80431)

FKIE_CVE-2026-80431

GHSA-FX7R-Q727-J825

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