Vulnerability-Lookup

GHSA-68QR-37MV-CWHV

Vulnerability from github – Published: 2026-10-14 12:31 – Updated: 2026-10-14 12:31

Details

A flaw was found in BusyBox's dpkg-deb archive extraction. The ar archive handler flushes deferred symlinks after each archive member, unlike the tar, cpio, and unzip handlers which flush once after the last member. A specially crafted .deb archive with two data.tar members can exploit this ordering: the first member declares a symlink pointing to an absolute path (e.g., '/'), which is deferred as unsafe but flushed after the first member. The second member declares a regular file whose path traverses the now-live symlink, resulting in a file being written outside the intended extraction directory. This could allow an attacker to write arbitrary files to arbitrary locations when a user extracts a crafted .deb package.

Severity

7.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-90954"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-14T10:17:57Z",
    "severity": "HIGH"
  },
  "details": "A flaw was found in BusyBox\u0027s dpkg-deb archive extraction. The ar archive handler flushes deferred symlinks after each archive member, unlike the tar, cpio, and unzip handlers which flush once after the last member. A specially crafted .deb archive with two data.tar members can exploit this ordering: the first member declares a symlink pointing to an absolute path (e.g., \u0027/\u0027), which is deferred as unsafe but flushed after the first member. The second member declares a regular file whose path traverses the now-live symlink, resulting in a file being written outside the intended extraction directory. This could allow an attacker to write arbitrary files to arbitrary locations when a user extracts a crafted .deb package.",
  "id": "GHSA-68qr-37mv-cwhv",
  "modified": "2026-10-14T12:31:32Z",
  "published": "2026-10-14T12:31:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90954"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2026-90954"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2533007"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-90954 (GCVE-0-2026-90954)

Vulnerability from cvelistv5 – Published: 2026-10-14 10:00 – Updated: 2026-10-14 10:00

Title

Busybox: busybox: dpkg-deb extraction-root escape via per-ar-member deferred symlink flush

Summary

Severity

7.8 (High)


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

CWE

CWE-59 - Improper Link Resolution Before File Access ('Link Following')

Assigner

redhat CNA under the redhat root

CNA scorecard B 82/100 over 1021 records in the last 180 days details

References

2 references

URL	Tags
https://access.redhat.com/security/cve/CVE-2026-90954	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2533007	issue-trackingx_refsource_REDHAT

Impacted products

1 product

Vendor	Product	Version
Red Hat	Red Hat Hardened Images	cpe:/a:redhat:hummingbird:1

Date Public

2026-10-14 08:00

Credits

Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue.

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:hummingbird:1"
          ],
          "defaultStatus": "affected",
          "packageName": "busybox",
          "product": "Red Hat Hardened Images",
          "vendor": "Red Hat"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue."
        }
      ],
      "datePublic": "2026-10-14T08:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "A flaw was found in BusyBox\u0027s dpkg-deb archive extraction. The ar archive handler flushes deferred symlinks after each archive member, unlike the tar, cpio, and unzip handlers which flush once after the last member. A specially crafted .deb archive with two data.tar members can exploit this ordering: the first member declares a symlink pointing to an absolute path (e.g., \u0027/\u0027), which is deferred as unsafe but flushed after the first member. The second member declares a regular file whose path traverses the now-live symlink, resulting in a file being written outside the intended extraction directory. This could allow an attacker to write arbitrary files to arbitrary locations when a user extracts a crafted .deb package."
        }
      ],
      "metrics": [
        {
          "other": {
            "content": {
              "namespace": "https://access.redhat.com/security/updates/classification/",
              "value": "Important"
            },
            "type": "Red Hat severity rating"
          }
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-59",
              "description": "Improper Link Resolution Before File Access (\u0027Link Following\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-14T10:00:08.215Z",
        "orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "shortName": "redhat"
      },
      "references": [
        {
          "tags": [
            "vdb-entry",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/security/cve/CVE-2026-90954"
        },
        {
          "name": "RHBZ#2533007",
          "tags": [
            "issue-tracking",
            "x_refsource_REDHAT"
          ],
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2533007"
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2026-09-14T00:00:00.000Z",
          "value": "Reported to Red Hat."
        },
        {
          "lang": "en",
          "time": "2026-10-14T08:00:00.000Z",
          "value": "Made public."
        }
      ],
      "title": "Busybox: busybox: dpkg-deb extraction-root escape via per-ar-member deferred symlink flush",
      "workarounds": [
        {
          "lang": "en",
          "value": "Do not use BusyBox dpkg-deb to extract untrusted .deb packages. Use Debian\u0027s reference dpkg-deb implementation, which treats the extraction root as a boundary and is not affected by this issue. If BusyBox dpkg-deb must be used, inspect .deb archives for multiple data.tar members before extraction (legitimate .deb packages contain exactly one data.tar member)."
        }
      ],
      "x_generator": {
        "engine": "cvelib 1.8.0"
      },
      "x_redhatCweChain": "CWE-59: Improper Link Resolution Before File Access (\u0027Link Following\u0027)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
    "assignerShortName": "redhat",
    "cveId": "CVE-2026-90954",
    "datePublished": "2026-10-14T10:00:08.215Z",
    "dateReserved": "2026-09-14T11:58:18.067Z",
    "dateUpdated": "2026-10-14T10:00:08.215Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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