{"api_version":"1","generated_at":"2026-09-12T05:51:54+00:00","cve":"CVE-2026-89542","urls":{"html":"https://cve.report/CVE-2026-89542","api":"https://cve.report/api/cve/CVE-2026-89542.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89542","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89542"},"summary":{"title":"SUNRPC: harden gss_krb5_unwrap_v2 against short tokens","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: harden gss_krb5_unwrap_v2 against short tokens\n\ngss_krb5_unwrap_v2() reads the EC and RRC header fields at ptr+4 and\nptr+6 before validating that the token is at least GSS_KRB5_TOK_HDR_LEN\n(16) bytes long, and its rotate_left() helper passes buf->len - base\nto xdr_buf_subsegment() without verifying that base <= buf->len. When\na caller hands in a sub-16-byte token, or a token whose declared len\nleaves base past the end of the buffer, three distinct failures follow:\n\n    gss_krb5_unwrap_v2(offset, len, buf)\n      ptr = buf->head[0].iov_base + offset\n      ec  = *(ptr + 4)              /* OOB read on short head */\n      rrc = *(ptr + 6)              /* OOB read on short head */\n      rotate_left(offset + 16, buf, rrc)\n        xdr_buf_subsegment(buf, &subbuf,\n                           base, buf->len - base)   /* u32 wrap when base > len */\n        _rotate_left(&subbuf, shift)\n          shift %= buf->len         /* divide-by-zero when base == len */\n\nAfter decryption, the cleanup arithmetic has the same shape:\n\n    movelen = min_t(unsigned int, buf->head[0].iov_len, len);\n    movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;\n    BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >\n                                            buf->head[0].iov_len);\n\nThe BUG_ON re-adds the value just subtracted, so it reduces to\nmin(A, B) > A and is permanently false; it cannot catch the unsigned\nunderflow of movelen, which then drives a ~UINT_MAX-byte memmove().\n\nAdd four defense-in-depth guards inside the unwrap core so it is safe\nregardless of what its callers validate:\n\n  - reject tokens with len - offset < GSS_KRB5_TOK_HDR_LEN before\n    touching ptr+4/ptr+6;\n  - bail from rotate_left() when buf->len <= base, covering both the\n    underflow and zero-length cases;\n  - return early from _rotate_left() when buf->len is zero, so the\n    shift %= buf->len modulo cannot fault;\n  - replace the dead BUG_ON with a live check that returns\n    GSS_S_DEFECTIVE_TOKEN before the movelen subtraction.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:37","updated_at":"2026-09-11 20:19:37"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/806584a4b67a7233870c33e5b8f872e76dd02988","name":"https://git.kernel.org/stable/c/806584a4b67a7233870c33e5b8f872e76dd02988","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6959297aaa9572783d620a226d73c3fb94494888","name":"https://git.kernel.org/stable/c/6959297aaa9572783d620a226d73c3fb94494888","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a7894e10572d53eb10109b8d07459cc8d3435811","name":"https://git.kernel.org/stable/c/a7894e10572d53eb10109b8d07459cc8d3435811","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dddcb0f4b7e27fac16a78ea9a1c8ec2e8a241087","name":"https://git.kernel.org/stable/c/dddcb0f4b7e27fac16a78ea9a1c8ec2e8a241087","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89542","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89542","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected de9c17eb4a912c9028f7b470eb80815144883b26 dddcb0f4b7e27fac16a78ea9a1c8ec2e8a241087 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected de9c17eb4a912c9028f7b470eb80815144883b26 806584a4b67a7233870c33e5b8f872e76dd02988 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected de9c17eb4a912c9028f7b470eb80815144883b26 a7894e10572d53eb10109b8d07459cc8d3435811 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected de9c17eb4a912c9028f7b470eb80815144883b26 6959297aaa9572783d620a226d73c3fb94494888 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.35","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.35 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/sunrpc/auth_gss/gss_krb5_wrap.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"dddcb0f4b7e27fac16a78ea9a1c8ec2e8a241087","status":"affected","version":"de9c17eb4a912c9028f7b470eb80815144883b26","versionType":"git"},{"lessThan":"806584a4b67a7233870c33e5b8f872e76dd02988","status":"affected","version":"de9c17eb4a912c9028f7b470eb80815144883b26","versionType":"git"},{"lessThan":"a7894e10572d53eb10109b8d07459cc8d3435811","status":"affected","version":"de9c17eb4a912c9028f7b470eb80815144883b26","versionType":"git"},{"lessThan":"6959297aaa9572783d620a226d73c3fb94494888","status":"affected","version":"de9c17eb4a912c9028f7b470eb80815144883b26","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/sunrpc/auth_gss/gss_krb5_wrap.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":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","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"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"2.6.35","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"2.6.35","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"2.6.35","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"2.6.35","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: harden gss_krb5_unwrap_v2 against short tokens\n\ngss_krb5_unwrap_v2() reads the EC and RRC header fields at ptr+4 and\nptr+6 before validating that the token is at least GSS_KRB5_TOK_HDR_LEN\n(16) bytes long, and its rotate_left() helper passes buf->len - base\nto xdr_buf_subsegment() without verifying that base <= buf->len. When\na caller hands in a sub-16-byte token, or a token whose declared len\nleaves base past the end of the buffer, three distinct failures follow:\n\n    gss_krb5_unwrap_v2(offset, len, buf)\n      ptr = buf->head[0].iov_base + offset\n      ec  = *(ptr + 4)              /* OOB read on short head */\n      rrc = *(ptr + 6)              /* OOB read on short head */\n      rotate_left(offset + 16, buf, rrc)\n        xdr_buf_subsegment(buf, &subbuf,\n                           base, buf->len - base)   /* u32 wrap when base > len */\n        _rotate_left(&subbuf, shift)\n          shift %= buf->len         /* divide-by-zero when base == len */\n\nAfter decryption, the cleanup arithmetic has the same shape:\n\n    movelen = min_t(unsigned int, buf->head[0].iov_len, len);\n    movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;\n    BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >\n                                            buf->head[0].iov_len);\n\nThe BUG_ON re-adds the value just subtracted, so it reduces to\nmin(A, B) > A and is permanently false; it cannot catch the unsigned\nunderflow of movelen, which then drives a ~UINT_MAX-byte memmove().\n\nAdd four defense-in-depth guards inside the unwrap core so it is safe\nregardless of what its callers validate:\n\n  - reject tokens with len - offset < GSS_KRB5_TOK_HDR_LEN before\n    touching ptr+4/ptr+6;\n  - bail from rotate_left() when buf->len <= base, covering both the\n    underflow and zero-length cases;\n  - return early from _rotate_left() when buf->len is zero, so the\n    shift %= buf->len modulo cannot fault;\n  - replace the dead BUG_ON with a live check that returns\n    GSS_S_DEFECTIVE_TOKEN before the movelen subtraction."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:44:18.931Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/dddcb0f4b7e27fac16a78ea9a1c8ec2e8a241087"},{"url":"https://git.kernel.org/stable/c/806584a4b67a7233870c33e5b8f872e76dd02988"},{"url":"https://git.kernel.org/stable/c/a7894e10572d53eb10109b8d07459cc8d3435811"},{"url":"https://git.kernel.org/stable/c/6959297aaa9572783d620a226d73c3fb94494888"}],"title":"SUNRPC: harden gss_krb5_unwrap_v2 against short tokens","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89542","datePublished":"2026-09-11T19:44:18.931Z","dateReserved":"2026-09-11T19:38:34.722Z","dateUpdated":"2026-09-11T19:44:18.931Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:37","lastModifiedDate":"2026-09-11 20:19:37","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89542","Ordinal":"1","Title":"SUNRPC: harden gss_krb5_unwrap_v2 against short tokens","CVE":"CVE-2026-89542","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89542","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: harden gss_krb5_unwrap_v2 against short tokens\n\ngss_krb5_unwrap_v2() reads the EC and RRC header fields at ptr+4 and\nptr+6 before validating that the token is at least GSS_KRB5_TOK_HDR_LEN\n(16) bytes long, and its rotate_left() helper passes buf->len - base\nto xdr_buf_subsegment() without verifying that base <= buf->len. When\na caller hands in a sub-16-byte token, or a token whose declared len\nleaves base past the end of the buffer, three distinct failures follow:\n\n    gss_krb5_unwrap_v2(offset, len, buf)\n      ptr = buf->head[0].iov_base + offset\n      ec  = *(ptr + 4)              /* OOB read on short head */\n      rrc = *(ptr + 6)              /* OOB read on short head */\n      rotate_left(offset + 16, buf, rrc)\n        xdr_buf_subsegment(buf, &subbuf,\n                           base, buf->len - base)   /* u32 wrap when base > len */\n        _rotate_left(&subbuf, shift)\n          shift %= buf->len         /* divide-by-zero when base == len */\n\nAfter decryption, the cleanup arithmetic has the same shape:\n\n    movelen = min_t(unsigned int, buf->head[0].iov_len, len);\n    movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;\n    BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >\n                                            buf->head[0].iov_len);\n\nThe BUG_ON re-adds the value just subtracted, so it reduces to\nmin(A, B) > A and is permanently false; it cannot catch the unsigned\nunderflow of movelen, which then drives a ~UINT_MAX-byte memmove().\n\nAdd four defense-in-depth guards inside the unwrap core so it is safe\nregardless of what its callers validate:\n\n  - reject tokens with len - offset < GSS_KRB5_TOK_HDR_LEN before\n    touching ptr+4/ptr+6;\n  - bail from rotate_left() when buf->len <= base, covering both the\n    underflow and zero-length cases;\n  - return early from _rotate_left() when buf->len is zero, so the\n    shift %= buf->len modulo cannot fault;\n  - replace the dead BUG_ON with a live check that returns\n    GSS_S_DEFECTIVE_TOKEN before the movelen subtraction.","Type":"Description","Title":"SUNRPC: harden gss_krb5_unwrap_v2 against short tokens"}]}}}