{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-90954", "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "state": "PUBLISHED", "assignerShortName": "redhat", "dateReserved": "2026-09-14T11:58:18.067Z", "datePublished": "2026-10-14T10:00:08.215Z", "dateUpdated": "2026-10-14T10:00:08.215Z"}, "containers": {"cna": {"title": "Busybox: busybox: dpkg-deb extraction-root escape via per-ar-member deferred symlink flush", "metrics": [{"other": {"content": {"value": "Important", "namespace": "https://access.redhat.com/security/updates/classification/"}, "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"}], "descriptions": [{"lang": "en", "value": "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."}], "affected": [{"vendor": "Red Hat", "product": "Red Hat Hardened Images", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "busybox", "defaultStatus": "affected", "cpes": ["cpe:/a:redhat:hummingbird:1"]}], "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-90954", "tags": ["vdb-entry", "x_refsource_REDHAT"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2533007", "name": "RHBZ#2533007", "tags": ["issue-tracking", "x_refsource_REDHAT"]}], "datePublic": "2026-10-14T08:00:00.000Z", "problemTypes": [{"descriptions": [{"cweId": "CWE-59", "description": "Improper Link Resolution Before File Access ('Link Following')", "lang": "en", "type": "CWE"}]}], "x_redhatCweChain": "CWE-59: Improper Link Resolution Before File Access ('Link Following')", "workarounds": [{"lang": "en", "value": "Do not use BusyBox dpkg-deb to extract untrusted .deb packages. Use Debian's 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)."}], "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."}], "credits": [{"lang": "en", "value": "Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue."}], "providerMetadata": {"orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "shortName": "redhat", "dateUpdated": "2026-10-14T10:00:08.215Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"affected": [{"affectedData": [{"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"}], "source": "secalert@redhat.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-90954", "lastModified": "2026-10-14T10:17:57.297", "metrics": {"cvssMetricV31": [{"cvssData": {"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"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "secalert@redhat.com", "type": "Primary"}]}, "published": "2026-10-14T10:17:57.297", "references": [{"source": "secalert@redhat.com", "url": "https://access.redhat.com/security/cve/CVE-2026-90954"}, {"source": "secalert@redhat.com", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2533007"}], "sourceIdentifier": "secalert@redhat.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-59"}], "source": "secalert@redhat.com", "type": "Primary"}]}

{"acknowledgement": "Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue.", "bugzilla": {"description": "busybox: busybox: dpkg-deb extraction-root escape via per-ar-member deferred symlink flush", "id": "2533007", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2533007"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.8", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-59", "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."], "mitigation": {"lang": "en:us", "value": "Do not use BusyBox dpkg-deb to extract untrusted .deb packages. Use Debian's 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)."}, "name": "CVE-2026-90954", "package_state": [{"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "busybox", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-10-14T08:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-90954\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-90954"], "statement": "Red Hat product impact analysis is pending. Fedora ships busybox with the dpkg and dpkg-deb applets enabled and is confirmed affected. RHEL does not ship busybox as a standard package. The vulnerability requires the victim to extract a crafted .deb file using BusyBox dpkg-deb; RPM-based systems do not normally process .deb files, which limits practical exposure on Red Hat platforms. However, busybox dpkg-deb may be used in cross-platform build environments, container image construction, and firmware unpacking workflows.", "threat_severity": "Important"}

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