[31661] in CVS-changelog-for-Kerberos-V5
krb5 commit [krb5-1.22]: Free call_arg on all AUTH_GSSAPI exit paths
daemon@ATHENA.MIT.EDU (ghudson@mit.edu)
Mon Nov 9 12:01:07 2026
From: ghudson@mit.edu
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Date: Mon, 9 Nov 2026 12:01:03 -0500 (EST)
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https://github.com/krb5/krb5/commit/93cb29865df33972c54d8b124123973856513f6f
commit 93cb29865df33972c54d8b124123973856513f6f
Author: Julien Rische <jrische@redhat.com>
Date: Wed Sep 9 15:30:01 2026 +0200
Free call_arg on all AUTH_GSSAPI exit paths
In gssrpc__svcauth_gssapi(), ensure that call_arg is released along
all exit paths by freeing it in the error handler.
CVE-2026-112321:
The AUTH_GSSAPI handler in lib/rpc/svc_auth_gssapi.c in MIT Kerberos 5
(aka krb5) does not free decoded arguments on certain error paths,
which allows remote attackers to cause a denial of service (memory
exhaustion in kadmind) via crafted AUTH_GSSAPI_INIT requests that
trigger authentication failures.
(cherry picked from commit 89ea06778fe893a8fdad483f7716fe8309521603)
ticket: 9246
version_fixed: 1.22.3
src/lib/rpc/svc_auth_gssapi.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/src/lib/rpc/svc_auth_gssapi.c b/src/lib/rpc/svc_auth_gssapi.c
index ac4b7a9ac..244265f01 100644
--- a/src/lib/rpc/svc_auth_gssapi.c
+++ b/src/lib/rpc/svc_auth_gssapi.c
@@ -190,6 +190,7 @@ enum auth_stat gssrpc__svcauth_gssapi(
/* use AUTH_NONE until there is a client_handle */
rqst->rq_xprt->xp_auth = &svc_auth_none;
+ memset(&call_arg, 0, sizeof(call_arg));
memset(&call_res, 0, sizeof(call_res));
creds.client_handle.length = 0;
creds.client_handle.value = NULL;
@@ -314,7 +315,6 @@ enum auth_stat gssrpc__svcauth_gssapi(
}
/* call is for us, deserialize arguments */
- memset(&call_arg, 0, sizeof(call_arg));
if (! svc_getargs(rqst->rq_xprt, (xdrproc_t)xdr_authgssapi_init_arg,
&call_arg)) {
PRINTF(("svcauth_gssapi: cannot decode args\n"));
@@ -454,8 +454,9 @@ enum auth_stat gssrpc__svcauth_gssapi(
gssstat = call_res.gss_major;
minor_stat = call_res.gss_minor;
- /* done with call args */
+ /* Done with call_arg (it may be reused for AUTH_GSSAPI_MSG). */
xdr_free((xdrproc_t)xdr_authgssapi_init_arg, &call_arg);
+ memset(&call_arg, 0, sizeof(call_arg));
PRINTF(("svcauth_gssapi: accept_sec_context returned %#x %#x\n",
call_res.gss_major, call_res.gss_minor));
@@ -591,14 +592,11 @@ enum auth_stat gssrpc__svcauth_gssapi(
switch (rqst->rq_proc) {
case AUTH_GSSAPI_MSG:
PRINTF(("svcauth_gssapi: GSSAPI_MSG, getting args\n"));
- memset(&call_arg, 0, sizeof(call_arg));
if (! svc_getargs(rqst->rq_xprt,
(xdrproc_t)xdr_authgssapi_init_arg,
&call_arg)) {
PRINTF(("svcauth_gssapi: cannot decode args\n"));
LOG_MISCERR("protocol error in call arguments");
- xdr_free((xdrproc_t)xdr_authgssapi_init_arg,
- &call_arg);
ret = AUTH_BADCRED;
goto error;
}
@@ -659,6 +657,7 @@ enum auth_stat gssrpc__svcauth_gssapi(
return AUTH_OK;
error:
+ xdr_free((xdrproc_t)xdr_authgssapi_init_arg, &call_arg);
if (creds.client_handle.length != 0) {
PRINTF(("svcauth_gssapi: freeing client_handle len %d\n",
(int) creds.client_handle.length));
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