{"api_version":"1","generated_at":"2026-09-12T11:24:01+00:00","cve":"CVE-2026-89538","urls":{"html":"https://cve.report/CVE-2026-89538","api":"https://cve.report/api/cve/CVE-2026-89538.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89538","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89538"},"summary":{"title":"SUNRPC: Reject krb5 v2 wrap tokens with oversized ec field","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject krb5 v2 wrap tokens with oversized ec field\n\ngss_krb5_unwrap_v2() sets buf->len to a logical\nlength, which can be much smaller than head[0].iov_len\n(the allocated receive-page capacity).  It then calls\nxdr_buf_trim() with a trim length derived from the 16-bit\n\"extra count\" (ec) field in the Kerberos v2 token header.\n\nThe ec field is authenticated by the post-decrypt memcmp()\nagainst the encrypted header copy, so a randomly-mutated\nvalue is rejected.  However, any peer holding a valid GSS\ncontext can legitimately encrypt a token whose ec exceeds\nthe plaintext length.  Per RFC 4121, such a token is\nstructurally malformed.\n\nAlthough xdr_buf_trim() now clamps the buf->len subtraction\nto avoid unsigned underflow, the buffer is still left in a\nsemantically invalid state (zero length, inconsistent iov\nlengths) when ec is oversized.\n\nReject these tokens before calling xdr_buf_trim(), giving\ncallers a well-defined GSS_S_DEFECTIVE_TOKEN error and\nkeeping the xdr_buf internally consistent.  The wrapped blob\nbegins at a nonzero offset -- both callers pass len as\noffset + opaque_len -- so buf->len still counts the offset\nbytes that precede the blob.  Compare the trim length\nagainst the remaining wrapped segment, buf->len - offset,\nrather than the whole buffer; comparing against buf->len\nalone leaves an offset-wide window in which an oversized ec\npasses the test and xdr_buf_trim() cuts into the bytes ahead\nof the blob.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:36","updated_at":"2026-09-11 20:19:36"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f","name":"https://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9","name":"https://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6","name":"https://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91","name":"https://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89538","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89538","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cf4c024b908353fcc48309374d39e3399d67dfd1 dfcd81ab45613d45996fbf483d4ef54b0ec90ab9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cf4c024b908353fcc48309374d39e3399d67dfd1 1f9856af065b6158271687e9788407b9573fd16f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cf4c024b908353fcc48309374d39e3399d67dfd1 880effc943ed82d6811f272ed3307c222b40f4d6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cf4c024b908353fcc48309374d39e3399d67dfd1 ad484748eec0a66eac0f13ab53b3fbedb7333c91 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.13","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 3.13 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":"dfcd81ab45613d45996fbf483d4ef54b0ec90ab9","status":"affected","version":"cf4c024b908353fcc48309374d39e3399d67dfd1","versionType":"git"},{"lessThan":"1f9856af065b6158271687e9788407b9573fd16f","status":"affected","version":"cf4c024b908353fcc48309374d39e3399d67dfd1","versionType":"git"},{"lessThan":"880effc943ed82d6811f272ed3307c222b40f4d6","status":"affected","version":"cf4c024b908353fcc48309374d39e3399d67dfd1","versionType":"git"},{"lessThan":"ad484748eec0a66eac0f13ab53b3fbedb7333c91","status":"affected","version":"cf4c024b908353fcc48309374d39e3399d67dfd1","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":"3.13"},{"lessThan":"3.13","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":"3.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"3.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"3.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"3.13","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject krb5 v2 wrap tokens with oversized ec field\n\ngss_krb5_unwrap_v2() sets buf->len to a logical\nlength, which can be much smaller than head[0].iov_len\n(the allocated receive-page capacity).  It then calls\nxdr_buf_trim() with a trim length derived from the 16-bit\n\"extra count\" (ec) field in the Kerberos v2 token header.\n\nThe ec field is authenticated by the post-decrypt memcmp()\nagainst the encrypted header copy, so a randomly-mutated\nvalue is rejected.  However, any peer holding a valid GSS\ncontext can legitimately encrypt a token whose ec exceeds\nthe plaintext length.  Per RFC 4121, such a token is\nstructurally malformed.\n\nAlthough xdr_buf_trim() now clamps the buf->len subtraction\nto avoid unsigned underflow, the buffer is still left in a\nsemantically invalid state (zero length, inconsistent iov\nlengths) when ec is oversized.\n\nReject these tokens before calling xdr_buf_trim(), giving\ncallers a well-defined GSS_S_DEFECTIVE_TOKEN error and\nkeeping the xdr_buf internally consistent.  The wrapped blob\nbegins at a nonzero offset -- both callers pass len as\noffset + opaque_len -- so buf->len still counts the offset\nbytes that precede the blob.  Compare the trim length\nagainst the remaining wrapped segment, buf->len - offset,\nrather than the whole buffer; comparing against buf->len\nalone leaves an offset-wide window in which an oversized ec\npasses the test and xdr_buf_trim() cuts into the bytes ahead\nof the blob."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:44:15.953Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9"},{"url":"https://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f"},{"url":"https://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6"},{"url":"https://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91"}],"title":"SUNRPC: Reject krb5 v2 wrap tokens with oversized ec field","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89538","datePublished":"2026-09-11T19:44:15.953Z","dateReserved":"2026-09-11T19:38:34.721Z","dateUpdated":"2026-09-11T19:44:15.953Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:36","lastModifiedDate":"2026-09-11 20:19:36","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89538","Ordinal":"1","Title":"SUNRPC: Reject krb5 v2 wrap tokens with oversized ec field","CVE":"CVE-2026-89538","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89538","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject krb5 v2 wrap tokens with oversized ec field\n\ngss_krb5_unwrap_v2() sets buf->len to a logical\nlength, which can be much smaller than head[0].iov_len\n(the allocated receive-page capacity).  It then calls\nxdr_buf_trim() with a trim length derived from the 16-bit\n\"extra count\" (ec) field in the Kerberos v2 token header.\n\nThe ec field is authenticated by the post-decrypt memcmp()\nagainst the encrypted header copy, so a randomly-mutated\nvalue is rejected.  However, any peer holding a valid GSS\ncontext can legitimately encrypt a token whose ec exceeds\nthe plaintext length.  Per RFC 4121, such a token is\nstructurally malformed.\n\nAlthough xdr_buf_trim() now clamps the buf->len subtraction\nto avoid unsigned underflow, the buffer is still left in a\nsemantically invalid state (zero length, inconsistent iov\nlengths) when ec is oversized.\n\nReject these tokens before calling xdr_buf_trim(), giving\ncallers a well-defined GSS_S_DEFECTIVE_TOKEN error and\nkeeping the xdr_buf internally consistent.  The wrapped blob\nbegins at a nonzero offset -- both callers pass len as\noffset + opaque_len -- so buf->len still counts the offset\nbytes that precede the blob.  Compare the trim length\nagainst the remaining wrapped segment, buf->len - offset,\nrather than the whole buffer; comparing against buf->len\nalone leaves an offset-wide window in which an oversized ec\npasses the test and xdr_buf_trim() cuts into the bytes ahead\nof the blob.","Type":"Description","Title":"SUNRPC: Reject krb5 v2 wrap tokens with oversized ec field"}]}}}