Vulnerability-Lookup

CVE-2026-33018 (GCVE-0-2026-33018)

Vulnerability from cvelistv5 – Published: 2026-04-14 21:45 – Updated: 2026-04-16 13:53

Title

libsixel: Use-After-Free in load_gif()

Summary

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame->pixels between frames without consulting the object's reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.

Severity

7 (High)


                        
                          CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-416 - Use After Free

Assigner

GitHub_M

References

2 references

URL	Tags
https://github.com/saitoha/libsixel/security/advi…	x_refsource_CONFIRM
https://github.com/saitoha/libsixel/releases/tag/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
saitoha	libsixel	Affected: < 1.8.7-rc1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33018",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-16T13:52:34.921283Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-16T13:53:25.060Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "libsixel",
          "vendor": "saitoha",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.7-rc1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "libsixel is a SIXEL encoder/decoder implementation derived from kmiya\u0027s sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame-\u003epixels between frames without consulting the object\u0027s reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 7,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-416",
              "description": "CWE-416: Use After Free",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-14T21:45:42.261Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp"
        },
        {
          "name": "https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1"
        }
      ],
      "source": {
        "advisory": "GHSA-w46f-jr9f-rgvp",
        "discovery": "UNKNOWN"
      },
      "title": "libsixel: Use-After-Free in load_gif()"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-33018",
    "datePublished": "2026-04-14T21:45:42.261Z",
    "dateReserved": "2026-03-17T17:22:14.666Z",
    "dateUpdated": "2026-04-16T13:53:25.060Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-33018",
      "date": "2026-08-05",
      "epss": "0.00191",
      "percentile": "0.08995"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-33018\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-04-14T22:16:30.213\",\"lastModified\":\"2026-07-25T10:10:00.167\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"libsixel is a SIXEL encoder/decoder implementation derived from kmiya\u0027s sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame-\u003epixels between frames without consulting the object\u0027s reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.\"},{\"lang\":\"es\",\"value\":\"libsixel es una implementaci\u00f3n de codificador/decodificador SIXEL derivada de sixel de kmiya. Las versiones 1.8.7 y anteriores contienen una vulnerabilidad de uso despu\u00e9s de liberaci\u00f3n a trav\u00e9s de la funci\u00f3n load_gif() en fromgif.c, donde un \u00fanico objeto sixel_frame_t se reutiliza en todos los fotogramas de un GIF animado y gif_init_frame() libera y reasigna incondicionalmente frame -\u003e pixels entre fotogramas sin consultar el contador de referencias del objeto. Debido a que la API p\u00fablica proporciona expl\u00edcitamente sixel_frame_ref() para retener un fotograma y sixel_frame_get_pixels() para acceder al b\u00fafer de p\u00edxeles sin procesar, una devoluci\u00f3n de llamada que siga este patr\u00f3n de uso documentado mantendr\u00e1 un puntero colgante despu\u00e9s de que se decodifique el segundo fotograma, lo que resultar\u00e1 en un uso despu\u00e9s de liberaci\u00f3n en el heap confirmado por ASAN. Cualquier aplicaci\u00f3n que utilice sixel_helper_load_image_file() con una devoluci\u00f3n de llamada multifotograma para procesar GIFs animados proporcionados por el usuario se ve afectada, con un bloqueo fiable como el impacto m\u00ednimo y potencial de ejecuci\u00f3n de c\u00f3digo. Este problema ha sido solucionado en la versi\u00f3n 1.8.7-r1.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"saitoha\",\"product\":\"libsixel\",\"versions\":[{\"version\":\"\u003c 1.8.7-rc1\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H\",\"baseScore\":7.0,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.0,\"impactScore\":5.9}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-04-16T13:52:34.921283Z\",\"id\":\"CVE-2026-33018\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"no\"},{\"technicalImpact\":\"total\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:saitoha:libsixel:*:*:*:*:*:*:*:*\",\"versionEndExcluding\":\"1.8.7-r1\",\"matchCriteriaId\":\"E16EAA6A-544F-4D16-829D-1B7C9979EA6A\"}]}]}],\"references\":[{\"url\":\"https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Exploit\",\"Vendor Advisory\"]}]}}",
    "redhat_vex": {
      "current_release_date": "2026-06-28T07:29:50+00:00",
      "cve": "CVE-2026-33018",
      "id": "CVE-2026-33018",
      "initial_release_date": "2026-04-14T21:45:42.261000+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "libsixel: libsixel: Arbitrary code execution via Use-After-Free in GIF processing",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33018.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-04-15T13:41:24Z",
      "cve": "CVE-2026-33018",
      "id": "CVE-2026-33018",
      "initial_release_date": "2026-04-15T13:41:24Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-33018",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-33018.json",
      "version": "2"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-33018\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-04-16T13:52:34.921283Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-04-16T13:53:05.842Z\"}}], \"cna\": {\"title\": \"libsixel: Use-After-Free in load_gif()\", \"source\": {\"advisory\": \"GHSA-w46f-jr9f-rgvp\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"REQUIRED\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"HIGH\"}}], \"affected\": [{\"vendor\": \"saitoha\", \"product\": \"libsixel\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 1.8.7-rc1\"}]}], \"references\": [{\"url\": \"https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp\", \"name\": \"https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1\", \"name\": \"https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"libsixel is a SIXEL encoder/decoder implementation derived from kmiya\u0027s sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame-\u003epixels between frames without consulting the object\u0027s reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-416\", \"description\": \"CWE-416: Use After Free\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-04-14T21:45:42.261Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-33018\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-04-16T13:53:25.060Z\", \"dateReserved\": \"2026-03-17T17:22:14.666Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-04-14T21:45:42.261Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-33018

Vulnerability from fkie_nvd - Published: 2026-04-14 22:16 - Updated: 2026-06-17 10:36

Severity

7.0 (High) - CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1	Release Notes
	security-advisories@github.com	https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	saitoha	libsixel	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "libsixel",
          "vendor": "saitoha",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.7-rc1"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:saitoha:libsixel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "E16EAA6A-544F-4D16-829D-1B7C9979EA6A",
              "versionEndExcluding": "1.8.7-r1",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "libsixel is a SIXEL encoder/decoder implementation derived from kmiya\u0027s sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame-\u003epixels between frames without consulting the object\u0027s reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1."
    }
  ],
  "id": "CVE-2026-33018",
  "lastModified": "2026-06-17T10:36:47.327",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.0,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.0,
        "impactScore": 5.9,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-33018",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-16T13:52:34.921283Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-14T22:16:30.213",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

ubuntu-cve-2026-33018

Vulnerability from osv_ubuntu

Published

2026-04-14 22:16

Modified

2026-05-20 15:27

Summary

Details

Severity

7.0 (High)


                    
                      CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-33018	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-33018	REPORT
	https://github.com/saitoha/libsixel/security/advi…	REPORT
	https://github.com/saitoha/libsixel/releases/tag/…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libsixel-bin",
            "binary_version": "1.5.2-2"
          },
          {
            "binary_name": "libsixel1",
            "binary_version": "1.5.2-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "libsixel",
        "purl": "pkg:deb/ubuntu/libsixel@1.5.2-2?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.4.2-1",
        "1.5.2-2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libsixel-bin",
            "binary_version": "1.7.3-1"
          },
          {
            "binary_name": "libsixel-examples",
            "binary_version": "1.7.3-1"
          },
          {
            "binary_name": "libsixel1",
            "binary_version": "1.7.3-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "libsixel",
        "purl": "pkg:deb/ubuntu/libsixel@1.7.3-1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.5.2-2",
        "1.7.3-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libsixel-bin",
            "binary_version": "1.8.2-2.1"
          },
          {
            "binary_name": "libsixel-examples",
            "binary_version": "1.8.2-2.1"
          },
          {
            "binary_name": "libsixel1",
            "binary_version": "1.8.2-2.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "libsixel",
        "purl": "pkg:deb/ubuntu/libsixel@1.8.2-2.1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.2-1",
        "1.8.2-2.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libsixel-bin",
            "binary_version": "1.10.3-3"
          },
          {
            "binary_name": "libsixel-examples",
            "binary_version": "1.10.3-3"
          },
          {
            "binary_name": "libsixel1",
            "binary_version": "1.10.3-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "libsixel",
        "purl": "pkg:deb/ubuntu/libsixel@1.10.3-3?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.6-2",
        "1.10.3-2",
        "1.10.3-3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libsixel-bin",
            "binary_version": "1.10.3-3build1"
          },
          {
            "binary_name": "libsixel-examples",
            "binary_version": "1.10.3-3build1"
          },
          {
            "binary_name": "libsixel1",
            "binary_version": "1.10.3-3build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libsixel",
        "purl": "pkg:deb/ubuntu/libsixel@1.10.3-3build1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10.3-3",
        "1.10.3-3build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libsixel-bin",
            "binary_version": "1.10.5-1"
          },
          {
            "binary_name": "libsixel-examples",
            "binary_version": "1.10.5-1"
          },
          {
            "binary_name": "libsixel1",
            "binary_version": "1.10.5-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "libsixel",
        "purl": "pkg:deb/ubuntu/libsixel@1.10.5-1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10.5-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libsixel-bin",
            "binary_version": "1.10.5-1build1"
          },
          {
            "binary_name": "libsixel-examples",
            "binary_version": "1.10.5-1build1"
          },
          {
            "binary_name": "libsixel1",
            "binary_version": "1.10.5-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "libsixel",
        "purl": "pkg:deb/ubuntu/libsixel@1.10.5-1build1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10.5-1",
        "1.10.5-1build1"
      ]
    }
  ],
  "aliases": [],
  "details": "libsixel is a SIXEL encoder/decoder implementation derived from kmiya\u0027s sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame-\u003epixels between frames without consulting the object\u0027s reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.",
  "id": "UBUNTU-CVE-2026-33018",
  "modified": "2026-05-20T15:27:21Z",
  "published": "2026-04-14T22:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-33018"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-33018"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-33018"
  ]
}

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.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

CVE-2026-33018 (GCVE-0-2026-33018)

FKIE_CVE-2026-33018

ubuntu-cve-2026-33018

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature