Fix CVE-2026-35535

- Resolves: rhbz#2458153

0001-cve-2026-35535.patch

@@ -0,0 +1,142 @@
+From 3e474c2f201484be83d994ae10a4e20e8c81bb69 Mon Sep 17 00:00:00 2001
+From: "Todd C. Miller" <Todd.Miller@sudo.ws>
+Date: Sat, 8 Nov 2025 15:34:02 -0700
+Subject: [PATCH] exec_mailer: Set group as well as uid when running the mailer
+
+Also make a setuid(), setgid() or setgroups() failure fatal.
+
+Found by the ZeroPath AI Security Engineer <https://zeropath.com>
+
+Backported by Alejandro Lopez <allopez@redhat.com>
+---
+
+diff --git a/include/sudo_eventlog.h b/include/sudo_eventlog.h
+index eb9f4f4a8..485d2593e 100644
+--- a/include/sudo_eventlog.h
++++ b/include/sudo_eventlog.h
+@@ -80,6 +80,7 @@ struct eventlog_config {
+     int syslog_rejectpri;
+     int syslog_alertpri;
+     uid_t mailuid;
++    gid_t mailgid;
+     bool omit_hostname;
+     const char *logpath;
+     const char *time_fmt;
+@@ -151,7 +152,7 @@ void eventlog_set_syslog_rejectpri(int pri);
+ void eventlog_set_syslog_alertpri(int pri);
+ void eventlog_set_syslog_maxlen(size_t len);
+ void eventlog_set_file_maxlen(size_t len);
+-void eventlog_set_mailuid(uid_t uid);
++void eventlog_set_mailuser(uid_t uid, gid_t gid);
+ void eventlog_set_omit_hostname(bool omit_hostname);
+ void eventlog_set_logpath(const char *path);
+ void eventlog_set_time_fmt(const char *fmt);
+diff --git a/lib/eventlog/eventlog.c b/lib/eventlog/eventlog.c
+index f4a9f330d..2db2f251c 100644
+--- a/lib/eventlog/eventlog.c
++++ b/lib/eventlog/eventlog.c
+@@ -304,15 +304,13 @@ exec_mailer(int pipein)
+ 	syslog(LOG_ERR, _("unable to dup stdin: %m")); // -V618
+ 	sudo_debug_printf(SUDO_DEBUG_ERROR,
+ 	    "unable to dup stdin: %s", strerror(errno));
+-	sudo_debug_exit(__func__, __FILE__, __LINE__, sudo_debug_subsys);
+-	_exit(127);
++	goto bad;
+     }
+
+     /* Build up an argv based on the mailer path and flags */
+     if ((mflags = strdup(evl_conf->mailerflags)) == NULL) {
+ 	syslog(LOG_ERR, _("unable to allocate memory")); // -V618
+-	sudo_debug_exit(__func__, __FILE__, __LINE__, sudo_debug_subsys);
+-	_exit(127);
++	goto bad;
+     }
+     argv[0] = sudo_basename(mpath);
+
+@@ -331,11 +329,23 @@ exec_mailer(int pipein)
+     if (setuid(ROOT_UID) != 0) {
+ 	sudo_debug_printf(SUDO_DEBUG_ERROR, "unable to change uid to %u",
+ 	    ROOT_UID);
++	goto bad;
++    }
++    if (setgid(evl_conf->mailgid) != 0) {
++	sudo_debug_printf(SUDO_DEBUG_ERROR, "unable to change gid to %u",
++	    (unsigned int)evl_conf->mailgid);
++	goto bad;
++    }
++    if (setgroups(1, &evl_conf->mailgid) != 0) {
++	sudo_debug_printf(SUDO_DEBUG_ERROR, "unable to set groups to %u",
++	    (unsigned int)evl_conf->mailgid);
++	goto bad;
+     }
+     if (evl_conf->mailuid != ROOT_UID) {
+ 	if (setuid(evl_conf->mailuid) != 0) {
+ 	    sudo_debug_printf(SUDO_DEBUG_ERROR, "unable to change uid to %u",
+ 		(unsigned int)evl_conf->mailuid);
++	    goto bad;
+ 	}
+     }
+     sudo_debug_exit(__func__, __FILE__, __LINE__, sudo_debug_subsys);
+@@ -347,6 +357,9 @@ exec_mailer(int pipein)
+     sudo_debug_printf(SUDO_DEBUG_ERROR, "unable to execute %s: %s",
+ 	mpath, strerror(errno));
+     _exit(127);
++bad:
++    sudo_debug_exit(__func__, __FILE__, __LINE__, sudo_debug_subsys);
++    _exit(127);
+ }
+
+ /* Send a message to the mailto user */
+diff --git a/lib/eventlog/eventlog_conf.c b/lib/eventlog/eventlog_conf.c
+index bbc3daaac..3d37b632c 100644
+--- a/lib/eventlog/eventlog_conf.c
++++ b/lib/eventlog/eventlog_conf.c
+@@ -70,6 +70,7 @@ static struct eventlog_config evl_conf = {
+     MAXSYSLOGLEN,		/* syslog_maxlen */
+     0,				/* file_maxlen */
+     ROOT_UID,			/* mailuid */
++    ROOT_GID,			/* mailgid */
+     false,			/* omit_hostname */
+     _PATH_SUDO_LOGFILE,		/* logpath */
+     "%h %e %T",			/* time_fmt */
+@@ -151,9 +152,10 @@ eventlog_set_file_maxlen(size_t len)
+ }
+
+ void
+-eventlog_set_mailuid(uid_t uid)
++eventlog_set_mailuser(uid_t uid, gid_t gid)
+ {
+     evl_conf.mailuid = uid;
++    evl_conf.mailgid = gid;
+ }
+
+ void
+diff --git a/plugins/sudoers/logging.c b/plugins/sudoers/logging.c
+index ec092d14e..1626a28cb 100644
+--- a/plugins/sudoers/logging.c
++++ b/plugins/sudoers/logging.c
+@@ -1157,7 +1157,7 @@ init_eventlog_config(void)
+     eventlog_set_syslog_alertpri(def_syslog_badpri);
+     eventlog_set_syslog_maxlen(def_syslog_maxlen);
+     eventlog_set_file_maxlen(def_loglinelen);
+-    eventlog_set_mailuid(ROOT_UID);
++    eventlog_set_mailuser(ROOT_UID, ROOT_GID);
+     eventlog_set_omit_hostname(!def_log_host);
+     eventlog_set_logpath(def_logfile);
+     eventlog_set_time_fmt(def_log_year ? "%h %e %T %Y" : "%h %e %T");
+diff --git a/plugins/sudoers/policy.c b/plugins/sudoers/policy.c
+index af3210dda..706c492b7 100644
+--- a/plugins/sudoers/policy.c
++++ b/plugins/sudoers/policy.c
+@@ -639,7 +639,7 @@ sudoers_policy_deserialize_info(struct sudoers_context *ctx, void *v,
+     }
+
+ #ifdef NO_ROOT_MAILER
+-    eventlog_set_mailuid(ctx->user.uid);
++    eventlog_set_mailuser(ctx->user.uid, ctx->user.gid);
+ #endif
+
+     /* Dump settings and user info (XXX - plugin args) */
+--
+2.53.0
+

sudo.spec

@@ -4,9 +4,9 @@
 Summary: Allows restricted root access for specified users
 Name: sudo
 Version: 1.9.17
-# remove -b 3 after rebase !!!
+# Remove "-b 3" after rebase !!!
 # use "-p -e % {?extraver}" when beta
-# use "-e % {?extraver}"" when patch version
+# use "-e % {?extraver}" when patch version
 # use nothing special when normal version
 Release: %autorelease -e %{?extraver}
 License: ISC
@@ -30,6 +30,8 @@ BuildRequires: systemd-rpm-macros
 BuildRequires: gettext
 BuildRequires: zlib-devel
 
+Patch1: 0001-cve-2026-35535.patch
+
 %description
 Sudo (superuser do) allows a system administrator to give certain
 users (or groups of users) the ability to run some (or all) commands