{"id":"CVE-2026-89720","title":"kernel: ubifs: fix out-of-bounds read in signature length check (CVE-2026-89720)","summary":"A flaw was found in the Linux kernel's Unsorted Block Image File System (UBIFS). An incorrect bounds check in the ubifs_sb_verify_signature() function allows a crafted signed UBIFS image to declare a signature length larger than its actual…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":"CWE-125","vendor":"Red Hat","product":"Linux","affected":["Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < ab7405bd86331cc2dbc8201699d4adc33bea75e7","Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < 11abc34698cb3172badf8aa12e623f1bac98bbd8","Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < 8cc3da72cf57acb4b77442ea8cec48425dff7c06","Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < 37a9d25a563f5f9103282954ce573c4a61321e7c","Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < f76b79d6e42af20682495bccd22f72c7164b0018","Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < a1dc246f98bb94233effa4fa3ec7bf84700bb7d1","Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < 83e1aa9f5f906c9b1f4949d0521f0f950a159d96","Linux >= 817aa094842dfc3a6b98c9582d4a647827f66201 < 95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf","Linux 5.3"],"published":"2026-09-11","updated":"2026-09-15","sourceUpdated":"2026-09-15T20:24:19+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89720.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89720.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89720"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532147"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89720"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89720"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89720.mbox"},{"url":"https://git.kernel.org/stable/c/ab7405bd86331cc2dbc8201699d4adc33bea75e7"},{"url":"https://git.kernel.org/stable/c/11abc34698cb3172badf8aa12e623f1bac98bbd8"},{"url":"https://git.kernel.org/stable/c/8cc3da72cf57acb4b77442ea8cec48425dff7c06"},{"url":"https://git.kernel.org/stable/c/37a9d25a563f5f9103282954ce573c4a61321e7c"},{"url":"https://git.kernel.org/stable/c/f76b79d6e42af20682495bccd22f72c7164b0018"},{"url":"https://git.kernel.org/stable/c/a1dc246f98bb94233effa4fa3ec7bf84700bb7d1"},{"url":"https://git.kernel.org/stable/c/83e1aa9f5f906c9b1f4949d0521f0f950a159d96"},{"url":"https://git.kernel.org/stable/c/95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf"}],"tags":["csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.00182,"epssPercentile":0.08073,"scores":{"vendor":5.5,"cna":7.7},"ingestedAt":"2026-09-14T15:23:07.449Z","slug":"CVE-2026-89720","body":"## Overview\n\nA flaw was found in the Linux kernel's Unsorted Block Image File System (UBIFS). An incorrect bounds check in the ubifs_sb_verify_signature() function allows a crafted signed UBIFS image to declare a signature length larger than its actual size. This can lead to an out-of-bounds read when processing the signature, potentially causing information disclosure or a system crash (Denial of Service).\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89720.json)\n\n**kernel: ubifs: fix out-of-bounds read in signature length check** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-15.\n\nNot affected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 7\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\n## Remediation\n\nRefer to the advisory for fix availability.","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":205516,"id":"CVE-2026-89720","ts":1789576723093,"field":"cvss","old":"7.7","new":"5.5"},{"seq":205515,"id":"CVE-2026-89720","ts":1789576723093,"field":"severity","old":"high","new":"medium"},{"seq":197698,"id":"CVE-2026-89720","ts":1789384318456,"field":"cvss","old":"4.7","new":"7.7"},{"seq":197697,"id":"CVE-2026-89720","ts":1789384318456,"field":"severity","old":"medium","new":"high"},{"seq":183339,"id":"CVE-2026-89720","ts":1789356674945,"field":"cvss","old":"7.7","new":"4.7"},{"seq":183338,"id":"CVE-2026-89720","ts":1789356674945,"field":"severity","old":"high","new":"medium"},{"seq":153606,"id":"CVE-2026-89720","ts":1789285351468,"field":"cvss","old":null,"new":"7.7"},{"seq":153605,"id":"CVE-2026-89720","ts":1789285351468,"field":"severity","old":"none","new":"high"},{"seq":147686,"id":"CVE-2026-89720","ts":1789270211881,"field":"cvss","old":null,"new":"4.7"},{"seq":147685,"id":"CVE-2026-89720","ts":1789270211881,"field":"severity","old":"none","new":"medium"},{"seq":109438,"id":"CVE-2026-89720","ts":1789183731915,"field":"cvss","old":null,"new":"4.7"},{"seq":109437,"id":"CVE-2026-89720","ts":1789183731915,"field":"severity","old":"none","new":"medium"}]}