{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-89542", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-89542", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-09-11T19:44:18.931Z", "updatedAt": "2026-10-19T08:48:33.941Z", "importedAt": "2026-10-24T01:58:35.090Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "SUNRPC: harden gss_krb5_unwrap_v2 against short tokens", "summary": "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.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "299d281c7225ded15b28cb861a98d818d82787fc" }, { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "84ddbc8d084c0251d534f14f5d1a7da05be56404" }, { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "075d7cfc4df8c54cb202ba8b28420370c03ba9b6" }, { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "f2591660e0eb263c9415bf0d0bb1b111e62df7a4" }, { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "dddcb0f4b7e27fac16a78ea9a1c8ec2e8a241087" }, { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "806584a4b67a7233870c33e5b8f872e76dd02988" }, { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "a7894e10572d53eb10109b8d07459cc8d3435811" }, { "version": "de9c17eb4a912c9028f7b470eb80815144883b26", "status": "affected", "versionType": "git", "lessThan": "6959297aaa9572783d620a226d73c3fb94494888" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.35", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.35" }, { "version": "5.10.270", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.221", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.188", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.157", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.109", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.50", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.2.4", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }