SUNRPC: harden gss_krb5_unwrap_v2 against short tokens
In the Linux kernel, the following vulnerability has been resolved: SUNRPC: harden gss_krb5_unwrap_v2 against short tokens gss_krb5_unwrap_v2() reads the EC and RRC header fields at ptr+4 and ptr+6 before validating that the token is at least GSS_KRB5_TOK_HDR_LEN (16) bytes long, and its rotate_left() helper passes buf->len - base to xdr_buf_subsegment() without verifying that base <= buf->len. When a caller hands in a sub-16-byte token, or a token whose declared len leaves base past the end of the buffer, three distinct failures follow: gss_krb5_unwrap_v2(offset, len, buf) ptr = buf->head[0].iov_base + offset ec = *(ptr + 4) /* OOB read on short head */ rrc = *(ptr + 6) /* OOB read on short head */ rotate_left(offset + 16, buf, rrc) xdr_buf_subsegment(buf, &subbuf, base, buf->len - base) /* u32 wrap when base > len */ _rotate_left(&subbuf, shift) shift %= buf->len /* divide-by-zero when base == len */ After decryption, the cleanup arithmetic has the same shape: movelen = min_t(unsigned int, buf->head[0].iov_len, len); movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > buf->head[0].iov_len); The BUG_ON re-adds the value just subtracted, so it reduces to min(A, B) > A and is permanently false; it cannot catch the unsigned underflow of movelen, which then drives a ~UINT_MAX-byte memmove(). Add four defense-in-depth guards inside the unwrap core so it is safe regardless of what its callers validate: - reject tokens wi
CVE-2026-89542
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89542
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "299d281c7225ded15b28cb861a98d818d82787fc",
"versionType": "git"
},
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "84ddbc8d084c0251d534f14f5d1a7da05be56404",
"versionType": "git"
},
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "075d7cfc4df8c54cb202ba8b28420370c03ba9b6",
"versionType": "git"
},
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "f2591660e0eb263c9415bf0d0bb1b111e62df7a4",
"versionType": "git"
},
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "dddcb0f4b7e27fac16a78ea9a1c8ec2e8a241087",
"versionType": "git"
},
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "806584a4b67a7233870c33e5b8f872e76dd02988",
"versionType": "git"
},
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "a7894e10572d53eb10109b8d07459cc8d3435811",
"versionType": "git"
},
{
"status": "affected",
"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
"lessThan": "6959297aaa9572783d620a226d73c3fb94494888",
"versionType": "git"
}
],
"programFiles": [
"net/sunrpc/auth_gss/gss_krb5_wrap.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.35"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.35",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sunrpc/auth_gss/gss_krb5_wrap.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89542
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #35060 · Revision 1
- Added to Heist Feed
- Publisher date