SUNRPC: svcauth_gss: enforce krb5 token minimum length
In the Linux kernel, the following vulnerability has been resolved: SUNRPC: svcauth_gss: enforce krb5 token minimum length svcauth_gss_unwrap_priv() validates only an upper bound on the wire-supplied opaque length before handing the buffer to gss_unwrap(): if (len > xdr_stream_remaining(xdr)) goto unwrap_failed; offset = xdr_stream_pos(xdr); ... maj_stat = gss_unwrap(ctx, offset, offset + len, buf); The wire value `len` flows unchanged as the upper bound into the krb5 unwrap path, so a len in [0, 16] passes this check and is handed to gss_unwrap(). For a krb5 v2 context that lands in gss_krb5_unwrap_v2(), which reads the 16-byte RFC 4121 token header fields at ptr+4 and ptr+6 and then calls rotate_left() before any integrity check. With a sub-header length the header reads run past the token, and _rotate_left()'s `shift %= buf->len` path can divide by zero when buf->len has been driven to zero by the truncated token. A header-only token (len == 16) is equally invalid: with a non-zero RRC field and the opaque blob ending at the XDR buffer boundary, rotate_left() builds a zero-length subbuffer, reaching the same division. Reject the token at the server entry point before it reaches the krb5 unwrap core. A valid sealed RFC 4121 token must contain the 16-byte header plus at least some encrypted payload. Fix by adding a minimum-length check immediately after the existing upper-bound check: if (len <= GSS_KRB5_TOK_HDR_LEN) goto unwrap_failed;
CVE-2026-89550
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-2026-89550
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": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
"lessThan": "0ea5b0c7f212c2772d32c2b88287b89a9cdf6edd",
"versionType": "git"
},
{
"status": "affected",
"version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
"lessThan": "dd6afc6cab8c5d387d1ed2f069562ef7bdadd651",
"versionType": "git"
},
{
"status": "affected",
"version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
"lessThan": "de942dd8c2c8358bcad04ce44271954c48924423",
"versionType": "git"
},
{
"status": "affected",
"version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
"lessThan": "2eed1e6a976a44015c3ee78841fe336796e2b21c",
"versionType": "git"
},
{
"status": "affected",
"version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
"lessThan": "a919c5c88769cf8fb3ec071e6078d830bf512489",
"versionType": "git"
}
],
"programFiles": [
"net/sunrpc/auth_gss/svcauth_gss.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.18"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.18",
"versionType": "semver"
},
{
"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/svcauth_gss.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89550
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #35066 · Revision 1
- Added to Heist Feed
- Publisher date