ubuntu-cve-2026-4878
Vulnerability from osv_ubuntu
Published
2026-04-09 16:16
Modified
2026-06-24 00:16
Summary
Details

A flaw was found in libcap. A local unprivileged user can exploit a Time-of-check-to-time-of-use (TOCTOU) race condition in the cap_set_file() function. This allows an attacker with write access to a parent directory to redirect file capability updates to an attacker-controlled file. By doing so, capabilities can be injected into or stripped from unintended executables, leading to privilege escalation.

Severity
6.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
7.0 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libcap2",
            "binary_version": "1:2.24-0ubuntu2+esm2"
          },
          {
            "binary_name": "libcap2-bin",
            "binary_version": "1:2.24-0ubuntu2+esm2"
          },
          {
            "binary_name": "libpam-cap",
            "binary_version": "1:2.24-0ubuntu2+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "libcap2",
        "purl": "pkg:deb/ubuntu/libcap2@1:2.24-0ubuntu2+esm2?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.24-0ubuntu2+esm2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:2.22-1.2ubuntu2",
        "1:2.24-0ubuntu1",
        "1:2.24-0ubuntu2",
        "1:2.24-0ubuntu2+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libcap2",
            "binary_version": "1:2.24-12ubuntu0.1~esm2"
          },
          {
            "binary_name": "libcap2-bin",
            "binary_version": "1:2.24-12ubuntu0.1~esm2"
          },
          {
            "binary_name": "libpam-cap",
            "binary_version": "1:2.24-12ubuntu0.1~esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "libcap2",
        "purl": "pkg:deb/ubuntu/libcap2@1:2.24-12ubuntu0.1~esm2?arch=source\u0026distro=esm-infra-legacy/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.24-12ubuntu0.1~esm2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:2.24-9",
        "1:2.24-12",
        "1:2.24-12ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libcap2",
            "binary_version": "1:2.25-1.2ubuntu0.1~esm2"
          },
          {
            "binary_name": "libcap2-bin",
            "binary_version": "1:2.25-1.2ubuntu0.1~esm2"
          },
          {
            "binary_name": "libpam-cap",
            "binary_version": "1:2.25-1.2ubuntu0.1~esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "libcap2",
        "purl": "pkg:deb/ubuntu/libcap2@1:2.25-1.2ubuntu0.1~esm2?arch=source\u0026distro=esm-infra/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.25-1.2ubuntu0.1~esm2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:2.25-1.1",
        "1:2.25-1.2",
        "1:2.25-1.2ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libcap2",
            "binary_version": "1:2.32-1ubuntu0.2+esm1"
          },
          {
            "binary_name": "libcap2-bin",
            "binary_version": "1:2.32-1ubuntu0.2+esm1"
          },
          {
            "binary_name": "libpam-cap",
            "binary_version": "1:2.32-1ubuntu0.2+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "libcap2",
        "purl": "pkg:deb/ubuntu/libcap2@1:2.32-1ubuntu0.2+esm1?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.32-1ubuntu0.2+esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:2.25-2",
        "1:2.27-1",
        "1:2.32-1",
        "1:2.32-1ubuntu0.1",
        "1:2.32-1ubuntu0.2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libcap2",
            "binary_version": "1:2.44-1ubuntu0.22.04.3"
          },
          {
            "binary_name": "libcap2-bin",
            "binary_version": "1:2.44-1ubuntu0.22.04.3"
          },
          {
            "binary_name": "libpam-cap",
            "binary_version": "1:2.44-1ubuntu0.22.04.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "libcap2",
        "purl": "pkg:deb/ubuntu/libcap2@1:2.44-1ubuntu0.22.04.3?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.44-1ubuntu0.22.04.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:2.44-1build1",
        "1:2.44-1build2",
        "1:2.44-1build3",
        "1:2.44-1ubuntu0.22.04.1",
        "1:2.44-1ubuntu0.22.04.2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libcap2",
            "binary_version": "1:2.66-5ubuntu2.4"
          },
          {
            "binary_name": "libcap2-bin",
            "binary_version": "1:2.66-5ubuntu2.4"
          },
          {
            "binary_name": "libpam-cap",
            "binary_version": "1:2.66-5ubuntu2.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libcap2",
        "purl": "pkg:deb/ubuntu/libcap2@1:2.66-5ubuntu2.4?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.66-5ubuntu2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:2.66-4ubuntu1",
        "1:2.66-5ubuntu1",
        "1:2.66-5ubuntu2",
        "1:2.66-5ubuntu2.1",
        "1:2.66-5ubuntu2.2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "golang-kernel-pub-linux-libs-security-libcap-dev",
            "binary_version": "1:2.75-7ubuntu2.2"
          },
          {
            "binary_name": "libcap2",
            "binary_version": "1:2.75-7ubuntu2.2"
          },
          {
            "binary_name": "libcap2-bin",
            "binary_version": "1:2.75-7ubuntu2.2"
          },
          {
            "binary_name": "libpam-cap",
            "binary_version": "1:2.75-7ubuntu2.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "libcap2",
        "purl": "pkg:deb/ubuntu/libcap2@1:2.75-7ubuntu2.2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:2.75-7ubuntu2.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:2.73-4ubuntu1",
        "1:2.75-7ubuntu1",
        "1:2.75-7ubuntu2"
      ]
    }
  ],
  "aliases": [],
  "details": "A flaw was found in libcap. A local unprivileged user can exploit a Time-of-check-to-time-of-use (TOCTOU) race condition in the `cap_set_file()` function. This allows an attacker with write access to a parent directory to redirect file capability updates to an attacker-controlled file. By doing so, capabilities can be injected into or stripped from unintended executables, leading to privilege escalation.",
  "id": "UBUNTU-CVE-2026-4878",
  "modified": "2026-06-24T00:16:37Z",
  "published": "2026-04-09T16:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-4878"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-4878"
    },
    {
      "type": "REPORT",
      "url": "https://sites.google.com/site/fullycapable/release-notes-for-libcap#h.x4zn8j3lss6r"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/AndrewGMorgan/libcap_mirror/security/advisories/GHSA-f78v-p5hx-m7hh"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8193-1"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8193-2"
    }
  ],
  "related": [
    "USN-8193-1",
    "USN-8193-2"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-4878"
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.