{"id":"CVE-2026-89541","state":"PUBLISHED","title":"SUNRPC: harden gss_unwrap_resp_priv length checks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: harden gss_unwrap_resp_priv length checks\n\ngss_unwrap_resp_priv() validates the RPCSEC_GSS opaque length with\n\n    offset = (u8 *)(p) - (u8 *)head->iov_base;\n    if (offset + opaque_len > rcv_buf->len)\n            goto unwrap_failed;\n    maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset,\n                          offset + opaque_len, rcv_buf);\n\nBoth operands are u32 and the sum is computed in u32. A reply with\nopaque_len near 0xffffffff makes offset + opaque_len wrap to a small\nvalue that is below rcv_buf->len, so the bound check passes and\ngss_unwrap() is called with end < begin. The check also lacks a\nlower bound, so any opaque_len in [0, GSS_KRB5_TOK_HDR_LEN) is\naccepted and forwarded to gss_krb5_unwrap_v2(), whose pre-decrypt\nheader reads at ptr+4 and ptr+6 then run past the token.\n\nA krb5p NFS server returning a crafted RPCSEC_GSS reply can drive\nthe client into out-of-bounds reads in gss_krb5_unwrap_v2() and the\nrotate_left() loop that follows.\n\nFix by replacing the single combined check with three guards that\nare safe in u32 arithmetic and that enforce the RFC 4121 minimum\nouter token length:\n\n    if (offset > rcv_buf->len)\n            goto unwrap_failed;\n    if (opaque_len > rcv_buf->len - offset)\n            goto unwrap_failed;\n    if (opaque_len < GSS_KRB5_TOK_HDR_LEN)\n            goto unwrap_failed;\n\nThe first guard makes the subtraction in the second guard\nunconditionally safe; offset is derived from a successful\nxdr_inline_decode() in the head kvec, so in practice it already\nsatisfies the bound. The floor mirrors the server-side check added\nin commit 5b757c2e57a5 (\"SUNRPC: svcauth_gss: enforce krb5 token\nminimum length\").","publishedAt":"2026-09-11T19:44:18.188Z","updatedAt":"2026-10-19T08:48:32.929Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"3691c4b3488d8ca046b9941e5be30c626dbbbb50","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"85fa6b12e8f439739ac36ef2aad925f37c8b976a","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"401f6a5b338d05bb1069ad814d9f77e3c367854f","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"81fd7654a8429718adfcb2a7e03496077f547ed0","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"89a15a50f84d32d4b99db86f957427fcbe20a99a","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"ebcbd2523a8524c3d24e111cdbed8e271d910269","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"d395c30d570ca6168f0297b191709927d1258273","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"87831b92112c81db251d46756d65daa4f91af6a2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sunrpc/auth_gss/auth_gss.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.15","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sunrpc/auth_gss/auth_gss.c"]}],"references":["https://git.kernel.org/stable/c/3691c4b3488d8ca046b9941e5be30c626dbbbb50","https://git.kernel.org/stable/c/85fa6b12e8f439739ac36ef2aad925f37c8b976a","https://git.kernel.org/stable/c/401f6a5b338d05bb1069ad814d9f77e3c367854f","https://git.kernel.org/stable/c/81fd7654a8429718adfcb2a7e03496077f547ed0","https://git.kernel.org/stable/c/89a15a50f84d32d4b99db86f957427fcbe20a99a","https://git.kernel.org/stable/c/ebcbd2523a8524c3d24e111cdbed8e271d910269","https://git.kernel.org/stable/c/d395c30d570ca6168f0297b191709927d1258273","https://git.kernel.org/stable/c/87831b92112c81db251d46756d65daa4f91af6a2"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89541.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89541","state":"PUBLISHED","datePublished":"2026-09-11T19:44:18.188Z","dateUpdated":"2026-10-19T08:48:32.929Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.721Z"},"containers":{"cna":{"title":"SUNRPC: harden gss_unwrap_resp_priv length checks","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: harden gss_unwrap_resp_priv length checks\n\ngss_unwrap_resp_priv() validates the RPCSEC_GSS opaque length with\n\n    offset = (u8 *)(p) - (u8 *)head->iov_base;\n    if (offset + opaque_len > rcv_buf->len)\n            goto unwrap_failed;\n    maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset,\n                          offset + opaque_len, rcv_buf);\n\nBoth operands are u32 and the sum is computed in u32. A reply with\nopaque_len near 0xffffffff makes offset + opaque_len wrap to a small\nvalue that is below rcv_buf->len, so the bound check passes and\ngss_unwrap() is called with end < begin. The check also lacks a\nlower bound, so any opaque_len in [0, GSS_KRB5_TOK_HDR_LEN) is\naccepted and forwarded to gss_krb5_unwrap_v2(), whose pre-decrypt\nheader reads at ptr+4 and ptr+6 then run past the token.\n\nA krb5p NFS server returning a crafted RPCSEC_GSS reply can drive\nthe client into out-of-bounds reads in gss_krb5_unwrap_v2() and the\nrotate_left() loop that follows.\n\nFix by replacing the single combined check with three guards that\nare safe in u32 arithmetic and that enforce the RFC 4121 minimum\nouter token length:\n\n    if (offset > rcv_buf->len)\n            goto unwrap_failed;\n    if (opaque_len > rcv_buf->len - offset)\n            goto unwrap_failed;\n    if (opaque_len < GSS_KRB5_TOK_HDR_LEN)\n            goto unwrap_failed;\n\nThe first guard makes the subtraction in the second guard\nunconditionally safe; offset is derived from a successful\nxdr_inline_decode() in the head kvec, so in practice it already\nsatisfies the bound. The floor mirrors the server-side check added\nin commit 5b757c2e57a5 (\"SUNRPC: svcauth_gss: enforce krb5 token\nminimum length\")."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"3691c4b3488d8ca046b9941e5be30c626dbbbb50","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"85fa6b12e8f439739ac36ef2aad925f37c8b976a","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"401f6a5b338d05bb1069ad814d9f77e3c367854f","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"81fd7654a8429718adfcb2a7e03496077f547ed0","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"89a15a50f84d32d4b99db86f957427fcbe20a99a","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"ebcbd2523a8524c3d24e111cdbed8e271d910269","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"d395c30d570ca6168f0297b191709927d1258273","versionType":"git"},{"version":"2d2da60c63b67174add32f06e8d54c3a0c5cd9cf","status":"affected","lessThan":"87831b92112c81db251d46756d65daa4f91af6a2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sunrpc/auth_gss/auth_gss.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.15","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sunrpc/auth_gss/auth_gss.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3691c4b3488d8ca046b9941e5be30c626dbbbb50"},{"url":"https://git.kernel.org/stable/c/85fa6b12e8f439739ac36ef2aad925f37c8b976a"},{"url":"https://git.kernel.org/stable/c/401f6a5b338d05bb1069ad814d9f77e3c367854f"},{"url":"https://git.kernel.org/stable/c/81fd7654a8429718adfcb2a7e03496077f547ed0"},{"url":"https://git.kernel.org/stable/c/89a15a50f84d32d4b99db86f957427fcbe20a99a"},{"url":"https://git.kernel.org/stable/c/ebcbd2523a8524c3d24e111cdbed8e271d910269"},{"url":"https://git.kernel.org/stable/c/d395c30d570ca6168f0297b191709927d1258273"},{"url":"https://git.kernel.org/stable/c/87831b92112c81db251d46756d65daa4f91af6a2"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - gss_unwrap_resp_priv() runs in the Linux NFS/SUNRPC client while decoding RPCSEC_GSS privacy (krb5p) replies; a malicious or compromised NFS server supplies the crafted opaque_len and wrap token over the existing TCP/UDP/RDMA RPC connection.\nAC:L - The attacker fully controls the reply, including opaque_len and the cleartext RFC 4121 header, and a single response can make offset+opaque_len wrap in u32 or fall below GSS_KRB5_TOK_HDR_LEN; no race or layout beyond the attacker’s control is required.\nPR:N - The attacker is the remote RPC/NFS peer that already holds the GSS session keys needed to pass gss_validate(); no local account, user namespace, or capability on the victim client is required.\nUI:N - Once a krb5p NFS mount or other SUNRPC GSS-privacy client is already in use, normal client RPCs elicit replies the attacker can craft; no extra victim action is needed at attack time.\nS:U - Out-of-bounds reads, rotate/decrypt memory corruption, and crashes stay inside the victim kernel’s SUNRPC client and do not cross a VM, IOMMU, or other security-authority boundary.\nC:H - A short or wrapped opaque_len makes gss_krb5_unwrap_v2() read past the token at ptr+4/ptr+6 and feeds rotate_left()/decrypt with wrapped lengths, disclosing adjacent kernel memory; unwrap cleanup can also memmove nearly UINT_MAX bytes.\nI:H - The same wrapped lengths drive rotate_left() writes, CBC/AEAD decrypt over an unbounded xdr subsegment (xdr_buf_subsegment’s error is ignored), and gss_krb5_unwrap_v2()’s unsigned movelen underflow into a near-4GiB memmove, enabling kernel memory corruption.\nA:H - rotate_left() can divide-by-zero on a zero-length subbuffer, spin in a multi-gigabyte kernel loop on a wrapped subsegment, or oops/panic on the huge memmove or out-of-bounds header access."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:48:32.929Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-89541","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:23:27.526748Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:26:42.189Z"}}]}}}