{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89720", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.752Z", "datePublished": "2026-09-11T19:46:32.923Z", "dateUpdated": "2026-10-19T08:51:33.033Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:51:33.033Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nubifs: fix out-of-bounds read in signature length check\n\nubifs_sb_verify_signature() bounds the on-disk ubifs_sig_node->len field\nbefore handing the signature payload to verify_pkcs7_signature(), but the\ncheck has the wrong sign:\n\n\tif (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node))\n\nThe signature bytes start sizeof(struct ubifs_sig_node) (UBIFS_SIG_NODE_SZ,\n64 bytes) into the node, so the payload is at most\n\n\tsnod->len - sizeof(struct ubifs_sig_node)\n\nbytes long. Adding the header size instead of subtracting it accepts a\ndeclared length up to 2 * UBIFS_SIG_NODE_SZ larger than the node actually\nholds -- past the end of c->sbuf, which is vmalloc(c->leb_size).\nverify_pkcs7_signature() -> pkcs7_parse_message() -> asn1_ber_decoder()\nis then handed that inflated length and reads beyond the allocation while\nwalking the DER headers. The node length comes straight from the mounted\nimage, so a crafted signed UBIFS image reaches this via\nubifs_read_superblock() before the signature is cryptographically checked.\n\nsnod->len is guaranteed to be >= UBIFS_SIG_NODE_SZ by the node scanner\n(c->ranges[UBIFS_SIG_NODE].min_len == UBIFS_SIG_NODE_SZ), so the corrected\nsubtraction cannot underflow. Legitimately signed images are unaffected: a\ncorrect superblock never declares a signature longer than the node it is\nembedded in." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.7, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The OOB read is reached only while mounting a local UBIFS/UBI volume (mount → ubifs_fill_super → mount_ubifs → ubifs_read_superblock → authenticate_sb_node → ubifs_sb_verify_signature). The inflated ubifs_sig_node->len comes from on-disk flash, not ksmbd, nfsd, or any received-packet path.\nAC:L - The attacker fully controls the on-disk SIG node size and signode->len. The inverted check accepts a payload up to snod->len+64; with a node filling the LEB that deterministically reads 128 bytes past vmalloc'd c->sbuf in asn1_ber_decoder(), with no race or uncontrolled layout.\nPR:N - Supplying the crafted authenticated image needs no account on the victim. ubifs_fs_type lacks FS_USERNS_MOUNT, so the CAP_SYS_ADMIN mount (boot-time auth_key mount on embedded, automotive, and IoT devices that use offline-signed UBIFS) is performed by the platform, matching the malicious-filesystem model.\nUI:N - Offline-signed UBIFS is verified automatically at mount; boot/fstab auto-mount with auth_key runs ubifs_sb_verify_signature in ubifs_read_superblock before any file access, so planting or presenting the crafted volume is sufficient with no separate victim click or open.\nS:U - The out-of-bounds read and any oops remain inside the mounting host kernel. This is a same-authority memory-safety issue, not a VM escape, IOMMU bypass, or other cross-boundary impact.\nC:H - verify_pkcs7_signature() → pkcs7_parse_message() → asn1_ber_decoder() walks an attacker-inflated length of up to 128 bytes past c->sbuf (vmalloc of the LEB). That is an out-of-bounds kernel read of adjacent vmalloc memory, which is Confidentiality High rather than a few-byte leak.\nI:N - The defect is an out-of-bounds read of PKCS#7/ASN.1 headers; the decoder copies those bytes only into newly allocated parse objects sized from the claimed length and does not write past any allocation or provide an arbitrary-write or control-flow primitive.\nA:H - Reading past the vmalloc LEB buffer into an unmapped vmalloc guard page oopses or panics the kernel during mount, and a crafted image can retrigger that crash on every boot or mount of the volume." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ubifs/auth.c" ], "versions": [ { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "ab7405bd86331cc2dbc8201699d4adc33bea75e7", "status": "affected", "versionType": "git" }, { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "11abc34698cb3172badf8aa12e623f1bac98bbd8", "status": "affected", "versionType": "git" }, { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "8cc3da72cf57acb4b77442ea8cec48425dff7c06", "status": "affected", "versionType": "git" }, { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "37a9d25a563f5f9103282954ce573c4a61321e7c", "status": "affected", "versionType": "git" }, { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "f76b79d6e42af20682495bccd22f72c7164b0018", "status": "affected", "versionType": "git" }, { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "a1dc246f98bb94233effa4fa3ec7bf84700bb7d1", "status": "affected", "versionType": "git" }, { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "83e1aa9f5f906c9b1f4949d0521f0f950a159d96", "status": "affected", "versionType": "git" }, { "version": "817aa094842dfc3a6b98c9582d4a647827f66201", "lessThan": "95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ubifs/auth.c" ], "versions": [ { "version": "5.3", "status": "affected" }, { "version": "0", "lessThan": "5.3", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "5.10.270" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "5.15.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "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" } ], "title": "ubifs: fix out-of-bounds read in signature length check", "x_generator": { "engine": "bippy-1.2.0" } } } }