diff --git a/.changelog/26703.txt b/.changelog/26703.txt
new file mode 100644
index 000000000..2e04af143
--- /dev/null
+++ b/.changelog/26703.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+exec: Correctly set the `LOGNAME` env var when the job specification user value is set
+```
diff --git a/drivers/shared/executor/executor_linux.go b/drivers/shared/executor/executor_linux.go
index 84fc3cc54..ed906a7e9 100644
--- a/drivers/shared/executor/executor_linux.go
+++ b/drivers/shared/executor/executor_linux.go
@@ -237,6 +237,7 @@ func (l *LibcontainerExecutor) Launch(command *ExecCommand) (*ProcessState, erro
 			return nil, err
 		}
 		process.Env = append(process.Env, fmt.Sprintf("USER=%s", u.Username))
+		process.Env = append(process.Env, fmt.Sprintf("LOGNAME=%s", u.Username))
 		process.Env = append(process.Env, fmt.Sprintf("HOME=%s", u.HomeDir))
 	}
 
diff --git a/drivers/shared/executor/executor_linux_test.go b/drivers/shared/executor/executor_linux_test.go
index 9dc94487f..d17b76798 100644
--- a/drivers/shared/executor/executor_linux_test.go
+++ b/drivers/shared/executor/executor_linux_test.go
@@ -865,6 +865,37 @@ func TestExecutor_UserEnv(t *testing.T) {
 	must.Eq(t, output, "runner")
 }
 
+func TestExecutor_LogNameEnv(t *testing.T) {
+	t.Parallel()
+	testutil.RequireCILinux(t)
+	testutil.ExecCompatible(t)
+
+	testExecCmd := testExecutorCommandWithChroot(t)
+	execCmd, allocDir := testExecCmd.command, testExecCmd.allocDir
+	execCmd.Cmd = "/bin/bash"
+	execCmd.Args = []string{"-c", "echo $LOGNAME"}
+	execCmd.User = "runner"
+	execCmd.ResourceLimits = true
+	defer allocDir.Destroy()
+
+	executor := NewExecutorWithIsolation(testlog.HCLogger(t), compute)
+	defer executor.Shutdown("SIGKILL", 0)
+
+	ps, err := executor.Launch(execCmd)
+	must.NoError(t, err)
+	must.NonZero(t, ps.Pid)
+
+	state, err := executor.Wait(context.Background())
+	must.NoError(t, err)
+	must.Zero(t, state.ExitCode)
+
+	_, ok := executor.(*LibcontainerExecutor)
+	must.True(t, ok)
+
+	output := strings.TrimSpace(testExecCmd.stdout.String())
+	must.Eq(t, output, "runner")
+}
+
 func TestExecCommand_getCgroupOr_off(t *testing.T) {
 	ci.Parallel(t)
 
diff --git a/drivers/shared/executor/executor_unix.go b/drivers/shared/executor/executor_unix.go
index c241a3bc4..960988212 100644
--- a/drivers/shared/executor/executor_unix.go
+++ b/drivers/shared/executor/executor_unix.go
@@ -101,8 +101,9 @@ func setCmdUser(cmd *exec.Cmd, userid string) error {
 	cmd.SysProcAttr.Credential.Gid = uint32(gid)
 	cmd.SysProcAttr.Credential.Groups = gids
 
-	// Override HOME and USER environment variables
+	// Override USER, LOGNAME, and HOME environment variables.
 	cmd.Env = append(cmd.Env, fmt.Sprintf("USER=%s", u.Username))
+	cmd.Env = append(cmd.Env, fmt.Sprintf("LOGNAME=%s", u.Username))
 	cmd.Env = append(cmd.Env, fmt.Sprintf("HOME=%s", u.HomeDir))
 
 	return nil
diff --git a/website/content/docs/job-specification/task.mdx b/website/content/docs/job-specification/task.mdx
index df1e14b23..fe3eb0ea8 100644
--- a/website/content/docs/job-specification/task.mdx
+++ b/website/content/docs/job-specification/task.mdx
@@ -110,8 +110,8 @@ job "docs" {
   [Docker][] images specify their own default users. Clients can restrict
   [which drivers][user_drivers] are allowed to run tasks as [certain
   users][user_denylist]. On UNIX-like systems, setting `user` also affects
-  the environment variables `HOME` and `USER` available to the task.  On
-  Windows, when Nomad is running as a [system service][service] for the
+  the environment variables `HOME`, `USER`, and `LOGNAME` available to the task.
+  On Windows, when Nomad is running as a [system service][service] for the
   [`raw_exec`][raw_exec] driver, you may specify a less-privileged service user.
   For example, `NT AUTHORITY\LocalService`, `NT AUTHORITY\NetworkService`.
 
diff --git a/website/content/docs/reference/runtime-environment-settings.mdx b/website/content/docs/reference/runtime-environment-settings.mdx
index 2773d7cc0..4d35a2f36 100644
--- a/website/content/docs/reference/runtime-environment-settings.mdx
+++ b/website/content/docs/reference/runtime-environment-settings.mdx
@@ -112,9 +112,9 @@ behavior.
 
 Nomad passes the environment variables defined in the client host to tasks
 when using the `exec`, `raw_exec`, and `java` task drivers. Nomad also modifies
-`HOME` and `USER` variables for tasks that have the `user` parameter set, to
-reflect the set username. The variables that are passed to the tasks can be
-controlled using the client configuration [`env.denylist`][].
+`HOME`, `USER`, and `LOGNAME` variables for tasks that have the `user` parameter
+set, to reflect the set username. The variables that are passed to the tasks can
+be controlled using the client configuration [`env.denylist`][].
 
 [jobspec]: /nomad/docs/job-specification 'Nomad Job Specification'
 [filesystem internals]: /nomad/docs/concepts/filesystem