Vulnerability-Lookup

CVE-2026-56390 (GCVE-0-2026-56390)

Vulnerability from cvelistv5 – Published: 2026-07-29 09:40 – Updated: 2026-07-29 12:15 X_Open Source

Title

Arbitrary Output Location Change in GNU Bison

Summary

GNU Bison improperly handles grammar‑defined output paths. Grammar directives such as %output and %header allow specifying file paths, which are accepted without restriction and override caller‑supplied output options. When processing attacker-supplied grammar, this behavior allows directing generated files to arbitrary writable locations on the filesystem, potentially overwriting existing files accessible to the Bison process. Maintainers of this project were notified about this vulnerability, and fixed the issue in commit 8d101c19d4d9aaedf83a448c925513742d4efcf0. However, they did not provide vulnerable version range. Version 3.8.2 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.

Severity

4.6 (Medium)


                        
                          CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-73 - External Control of File Name or Path

Assigner

CERT-PL

References

3 references

URL	Tags
https://cert.pl/en/posts/2026/07/CVE-2026-56389	third-party-advisory
https://cgit.git.savannah.gnu.org/cgit/bison.git/	patch
https://cgit.git.savannah.gnu.org/cgit/bison.git/…	patch

Impacted products

1 product

Vendor	Product	Version
GNU	Bison	Affected: 3.8.2 (semver)

Credits

Michał Majchrowicz (AFINE Team) Marcin Wyczechowski (AFINE Team)

Show details on NVD website

JSON

To clipboard

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GHSA-3PCJ-VQW8-47JM

Vulnerability from github – Published: 2026-07-29 12:31 – Updated: 2026-07-29 12:31

Details

Maintainers of this project were notified about this vulnerability, and fixed the issue in commit 8d101c19d4d9aaedf83a448c925513742d4efcf0. However, they did not provide vulnerable version range. Version 3.8.2 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.

Severity

4.6 (Medium)


                  
                    CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

Show details on source website

JSON

To clipboard

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    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-29T11:16:49Z",
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  },
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  "id": "GHSA-3pcj-vqw8-47jm",
  "modified": "2026-07-29T12:31:23Z",
  "published": "2026-07-29T12:31:23Z",
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    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56390"
    },
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      "type": "WEB",
      "url": "https://cert.pl/en/posts/2026/07/CVE-2026-56389"
    },
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      "type": "CVSS_V4"
    }
  ]
}

ubuntu-cve-2026-56390

Vulnerability from osv_ubuntu

Published

2026-07-30 00:00

Modified

2026-07-30 00:00

Summary

Details

Severity

4.6 (Medium)


                    
                      CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-56390	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-56390	REPORT
	https://cert.pl/en/posts/2026/07/CVE-2026-56389/	REPORT
	https://cgit.git.savannah.gnu.org/cgit/bison.git/…	REPORT
	https://cert.pl/en/posts/2026/07/CVE-2026-56389	REPORT
	https://cgit.git.savannah.gnu.org/cgit/bison.git/	REPORT

JSON

To clipboard

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        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.5.1+dfsg-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.4.1+dfsg-4",
        "2:3.4.2+dfsg-1",
        "2:3.5.1+dfsg-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.8.2+dfsg-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.8.2+dfsg-1build1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.7.6+dfsg-1build1",
        "2:3.8.2+dfsg-1",
        "2:3.8.2+dfsg-1build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.8.2+dfsg-1build2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.8.2+dfsg-1build2?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.8.2+dfsg-1build1",
        "2:3.8.2+dfsg-1build2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.8.2+dfsg-1build4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.8.2+dfsg-1build4?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.8.2+dfsg-1build3",
        "2:3.8.2+dfsg-1build4"
      ]
    }
  ],
  "aliases": [],
  "details": "GNU Bison improperly handles grammar\u2011defined output paths. Grammar directives such as %output and %header allow specifying file paths, which are accepted without restriction and override caller\u2011supplied output options. When processing attacker-supplied grammar, this behavior allows directing generated files to arbitrary writable locations on the filesystem, potentially overwriting existing files accessible to the Bison process. Maintainers of this project were notified about this vulnerability, and fixed the issue in commit\u00a08d101c19d4d9aaedf83a448c925513742d4efcf0. However, they did not provide vulnerable version range. Version 3.8.2 was tested\u00a0and confirmed as vulnerable, other versions were not tested but might also be vulnerable.",
  "id": "UBUNTU-CVE-2026-56390",
  "modified": "2026-07-30T00:00:00Z",
  "published": "2026-07-30T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-56390"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-56390"
    },
    {
      "type": "REPORT",
      "url": "https://cert.pl/en/posts/2026/07/CVE-2026-56389/"
    },
    {
      "type": "REPORT",
      "url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=8d101c19d4d9aaedf83a448c925513742d4efcf0"
    },
    {
      "type": "REPORT",
      "url": "https://cert.pl/en/posts/2026/07/CVE-2026-56389"
    },
    {
      "type": "REPORT",
      "url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-56390"
  ]
}

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-2026-56390 (GCVE-0-2026-56390)

GHSA-3PCJ-VQW8-47JM

ubuntu-cve-2026-56390

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature