{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89537", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.721Z", "datePublished": "2026-09-11T19:44:15.216Z", "dateUpdated": "2026-09-11T19:44:15.216Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-11T19:44:15.216Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2\n\ngss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags\nbyte at ptr[2], and padding at ptr[3..7], then passes\nptr + GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg().\nNone of these accesses check read_token->len first.\n\nThe minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus\nctx->krb5e->cksum_len (12-24, depending on the enctype). All callers\naccept shorter tokens from the wire:\n\n - gss_unwrap_resp_integ() enforces only an upper bound\n (offset + len <= rcv_buf->len) before allocating\n mic.data = kmalloc(len) and passing it to gss_verify_mic().\n A malicious NFS server can therefore supply a short checksum\n opaque, producing a small slab allocation that the Kerberos MIC\n verifier reads past.\n\n - gss_validate() enforces only len <= RPC_MAX_AUTH_SIZE (400)\n before passing the wire-supplied length to\n gss_validate_seqno_mic(), which constructs a mic xdr_netobj\n and calls gss_verify_mic().\n\n - svcauth_gss_verify_header() enforces only\n checksum.len >= XDR_UNIT (4 bytes) before dispatching to\n gss_verify_mic().\n\n - svcauth_gss_unwrap_integ() checks only that the checksum fits\n in gsd->gsd_scratch.\n\nAdd a length guard at the top of gss_krb5_verify_mic_v2(), before any\nptr[] access or scatterlist construction. Well-formed MIC tokens from\ngss_krb5_get_mic_v2() already have exactly GSS_KRB5_TOK_HDR_LEN +\ncksum_len bytes, so valid traffic is unaffected."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_unseal.c"], "versions": [{"version": "de9c17eb4a912c9028f7b470eb80815144883b26", "lessThan": "7a946b2e7207f968902f2147ab9b30726f82f7ab", "status": "affected", "versionType": "git"}, {"version": "de9c17eb4a912c9028f7b470eb80815144883b26", "lessThan": "b94f6719dcd9f7a609bc5f459f85795900e77d25", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_unseal.c"], "versions": [{"version": "2.6.35", "status": "affected"}, {"version": "0", "lessThan": "2.6.35", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3-rc1", "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": "2.6.35", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.35", "versionEndExcluding": "7.3-rc1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/7a946b2e7207f968902f2147ab9b30726f82f7ab"}, {"url": "https://git.kernel.org/stable/c/b94f6719dcd9f7a609bc5f459f85795900e77d25"}], "title": "SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_unseal.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "7a946b2e7207f968902f2147ab9b30726f82f7ab", "status": "affected", "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "versionType": "git"}, {"lessThan": "b94f6719dcd9f7a609bc5f459f85795900e77d25", "status": "affected", "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_unseal.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "2.6.35"}, {"lessThan": "2.6.35", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3-rc1", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2\n\ngss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags\nbyte at ptr[2], and padding at ptr[3..7], then passes\nptr + GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg().\nNone of these accesses check read_token->len first.\n\nThe minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus\nctx->krb5e->cksum_len (12-24, depending on the enctype). All callers\naccept shorter tokens from the wire:\n\n - gss_unwrap_resp_integ() enforces only an upper bound\n (offset + len <= rcv_buf->len) before allocating\n mic.data = kmalloc(len) and passing it to gss_verify_mic().\n A malicious NFS server can therefore supply a short checksum\n opaque, producing a small slab allocation that the Kerberos MIC\n verifier reads past.\n\n - gss_validate() enforces only len <= RPC_MAX_AUTH_SIZE (400)\n before passing the wire-supplied length to\n gss_validate_seqno_mic(), which constructs a mic xdr_netobj\n and calls gss_verify_mic().\n\n - svcauth_gss_verify_header() enforces only\n checksum.len >= XDR_UNIT (4 bytes) before dispatching to\n gss_verify_mic().\n\n - svcauth_gss_unwrap_integ() checks only that the checksum fits\n in gsd->gsd_scratch.\n\nAdd a length guard at the top of gss_krb5_verify_mic_v2(), before any\nptr[] access or scatterlist construction. Well-formed MIC tokens from\ngss_krb5_get_mic_v2() already have exactly GSS_KRB5_TOK_HDR_LEN +\ncksum_len bytes, so valid traffic is unaffected."}], "id": "CVE-2026-89537", "lastModified": "2026-09-11T20:19:36.733", "metrics": {}, "published": "2026-09-11T20:19:36.733", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7a946b2e7207f968902f2147ab9b30726f82f7ab"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b94f6719dcd9f7a609bc5f459f85795900e77d25"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel: Memory corruption in SUNRPC due to short Kerberos MIC tokens", "id": "2532109", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532109"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H", "status": "draft"}, "cwe": "CWE-125", "details": ["A flaw was found in the Linux kernel's SUNRPC implementation, specifically within the `gss_krb5_verify_mic_v2` function. A remote malicious Network File System (NFS) server could provide a specially crafted, short Kerberos Message Integrity Code (MIC) token. This could lead to the kernel reading past an allocated memory buffer, potentially causing a denial of service or information disclosure."], "name": "CVE-2026-89537", "public_date": "2026-09-11T19:44:15Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89537\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89537\nhttps://git.kernel.org/stable/c/7a946b2e7207f968902f2147ab9b30726f82f7ab\nhttps://git.kernel.org/stable/c/b94f6719dcd9f7a609bc5f459f85795900e77d25"], "threat_severity": "Moderate"}

{}