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efibootguard — security advisory

Type: advisorySources: OSVAdvisory ID: UBUNTU-CVE-2023-39950

efibootguard is a simple UEFI boot loader with support for safely switching between current and updated partition sets. Insufficient or missing validation and sanitization of input from untrustworthy bootloader environment files can cause crashes and probably also code injections into `bg_setenv`) or programs using `libebgenv`. This is triggered when the affected components try to modify a manipulated environment, in particular its user variables. Furthermore, `bg_printenv` may crash over invalid read accesses or report invalid results. Not affected by this issue is EFI Boot Guard's bootloader EFI binary. EFI Boot Guard release v0.15 contains required patches to sanitize and validate the bootloader environment prior to processing it in userspace. Its library and tools should be updated, so should programs statically linked against it. An update of the bootloader EFI executable is not required. The only way to prevent the issue with an unpatched EFI Boot Guard version is to avoid accesses to user variables, specifically modifications to them.

Products
efibootguard
Affected versions
0.15-1, 0.16-1, 0.16-2, 0.19-1, 0.22-2ubuntu1
Fixed versions
Not specified
CVEs
CVE-2023-39950
Confirmed fixed CVEs
Not specified
Updated in this feed
31 Oct 2026, 01:05 UTC · Revision 1

Source evidence

UBUNTU-CVE-2023-39950

core-osv · Original source

Published 14 Aug 2023, 21:15 UTC

efibootguard is a simple UEFI boot loader with support for safely switching between current and updated partition sets. Insufficient or missing validation and sanitization of input from untrustworthy bootloader environment files can cause crashes and probably also code injections into `bg_setenv`) or programs using `libebgenv`. This is triggered when the affected components try to modify a manipulated environment, in particular its user variables. Furthermore, `bg_printenv` may crash over invalid read accesses or report invalid results. Not affected by this issue is EFI Boot Guard's bootloader EFI binary. EFI Boot Guard release v0.15 contains required patches to sanitize and validate the bootloader environment prior to processing it in userspace. Its library and tools should be updated, so should programs statically linked against it. An update of the bootloader EFI executable is not required. The only way to prevent the issue with an unpatched EFI Boot Guard version is to avoid accesses to user variables, specifically modifications to them.

osv:UBUNTU-CVE-2023-39950

efibootguard

Fixed versions: Not specified

efibootguard

Fixed versions: Not specified

efibootguard

Fixed versions: Not specified

efibootguard

Fixed versions: Not specified

Complete source record
{
  "id": "61eb20eed9841877aad50392f6e8fe3d6c3be4262ae37cc9e1d143719f24b842",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2023-39950",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2023-39950",
    "summary": "efibootguard is a simple UEFI boot loader with support for safely switching between current and updated partition sets. Insufficient or missing validation and sanitization of input from untrustworthy bootloader environment files can cause crashes and probably also code injections into `bg_setenv`) or programs using `libebgenv`. This is triggered when the affected components try to modify a manipulated environment, in particular its user variables. Furthermore, `bg_printenv` may crash over invalid read accesses or report invalid results. Not affected by this issue is EFI Boot Guard's bootloader EFI binary. EFI Boot Guard release v0.15 contains required patches to sanitize and validate the bootloader environment prior to processing it in userspace. Its library and tools should be updated, so should programs statically linked against it. An update of the bootloader EFI executable is not required. The only way to prevent the issue with an unpatched EFI Boot Guard version is to avoid accesses to user variables, specifically modifications to them.",
    "evidence": "osv:UBUNTU-CVE-2023-39950",
    "products": [
      {
        "name": {
          "value": "efibootguard",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.15-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.16-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.16-2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "efibootguard",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.19-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "efibootguard",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.19-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "0.22-2ubuntu1",
            "evidence": "/affected/2/versions"
          }
        ]
      },
      {
        "name": {
          "value": "efibootguard",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.19-1",
            "evidence": "/affected/3/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "UBUNTU-CVE-2023-39950",
      "aliases": [
        "UBUNTU-CVE-2023-39950"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L"
        },
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "efibootguard",
            "purl": "pkg:deb/ubuntu/efibootguard?arch=source&distro=noble",
            "ecosystem": "Ubuntu:24.04:LTS"
          },
          "versions": [
            "0.15-1",
            "0.16-1",
            "0.16-2"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "efibootguard",
                "binary_version": "0.16-2"
              },
              {
                "binary_name": "libebgenv0",
                "binary_version": "0.16-2"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "efibootguard",
            "purl": "pkg:deb/ubuntu/efibootguard?arch=source&distro=questing",
            "ecosystem": "Ubuntu:25.10"
          },
          "versions": [
            "0.19-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "efibootguard",
                "binary_version": "0.19-1"
              },
              {
                "binary_name": "libebgenv0",
                "binary_version": "0.19-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "efibootguard",
            "purl": "pkg:deb/ubuntu/efibootguard?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "0.19-1",
            "0.22-2ubuntu1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "efibootguard",
                "binary_version": "0.22-2ubuntu1"
              },
              {
                "binary_name": "efibootguard-tools",
                "binary_version": "0.22-2ubuntu1"
              },
              {
                "binary_name": "libebgenv0",
                "binary_version": "0.22-2ubuntu1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "efibootguard",
            "purl": "pkg:deb/ubuntu/efibootguard?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "0.19-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "efibootguard",
                "binary_version": "0.19-1"
              },
              {
                "binary_name": "libebgenv0",
                "binary_version": "0.19-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:56:25.756531759Z",
      "provider": "osv",
      "upstream": [
        "CVE-2023-39950"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2023-39950",
        "https://github.com/siemens/efibootguard/commit/965d65c5751898c4bb094ef191b7387819423414",
        "https://github.com/siemens/efibootguard/commit/53dee61dc8b3a83c882e4bc9a0cfe7d6d73610c4",
        "https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md",
        "https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md#setting-user-variables",
        "https://github.com/siemens/efibootguard/blob/master/docs/API.md",
        "https://github.com/siemens/efibootguard/security/advisories/GHSA-j6pp-7g99-24m7",
        "https://github.com/siemens/efibootguard/tags",
        "https://www.cve.org/CVERecord?id=CVE-2023-39950"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2023-39950",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 355629,
  "published_at": "2023-08-14T21:15:00+00:00"
}